JP2007042569A - Signal transmission cable and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal transmission cable which is capable of transmitting differential signals with high reliability, a small variation in a characteristic impedance, and a reduced skew generation. <P>SOLUTION: This differential transmission cable comprises dielectric core layers 10a, 10b extending along the longitudinal direction of the cable; a first conductive layer 11 which is layered on an outer surface of the dielectric core layers 10a, 10b; a second conductive layer 12 which is layered on the other outer surface of the dielectric core layers 10a, 10b; and insulating material 13 for covering the dielectric core layers 10a, 10b and the first and second layers 11, 12. Each and all of the dielectric core layers 10a, 10b and the first and second layers 11, 12 have the same width, and each of the first and second layers 11, 12 has the same thickness. The insulating material 13 is covered with a shield layer 14, and the shield layer 14 is covered with a sheath 15, wherein the first and second layers 11, 12 form a pair of differential signal lines. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a signal transmission cable and a method for manufacturing the signal transmission cable, and more particularly to a signal transmission cable that can transmit a differential signal with high reliability at high speed.

  In recent years, information devices represented by network devices and personal computers have made remarkable progress, and the clock frequency is in the region exceeding GHz. Along with this, a signal transmission cable that connects devices is required to have a higher data transmission rate than ever before. In addition, with the increase in signal transmission speed, the number of signal lines accompanying an increase in data capacity has increased, and the demand for a high-speed multicore cable corresponding to the increase is high.

  FIG. 40 shows a configuration example of a conventional flexible multicore cable. As shown in FIG. 40, a plurality of central conductors 1001 that transmit signals are arranged in parallel on an insulating film 1000, and then the central conductor 1001 is covered with an insulating film 1002, thereby forming a microstrip structure.

  FIGS. 41A and 41B show a configuration example of a conventional multi-core coaxial cable. As shown in FIG. 41 (B), the multi-core coaxial cable includes a plurality of thin coaxial cables 1110. The plurality of fine coaxial cables 1110 are arranged in parallel and covered with an insulating film 1115 as a whole. ing. As shown in FIG. 41A, the thin coaxial cable 1110 has a central conductor 1111 for transmitting a signal covered with an insulating film 1112, and the outer periphery thereof is covered with an outer conductor 1113 and an insulating film 1114 serving as a ground plane. Yes.

The flexible multicore cable shown in FIG. 40 can be manufactured at a low cost because of its simple structure. However, since the central conductor 1001 is not completely shielded, it is easily affected by external noise and prevents deterioration in signal transmission quality. It ’s difficult.
The multi-core coaxial cable shown in FIG. 41A has high noise resistance, but is expensive because of its complicated structure.

  A technique relating to a method of manufacturing a multicore coaxial cable that solves such a problem is disclosed in Patent Document 1. 42 (A) to 42 (D) are diagrams showing a method for manufacturing the multi-core coaxial cable disclosed in Patent Document 1. FIG. As shown in FIG. 42A, after preparing the first insulating film 1121 having the outer conductors 1120 and 1122 ′ formed on both surfaces, the outer conductor 1122 ′ on the upper surface (the outer conductor 1122 ′ is not shown). Etching is performed to form a plurality of signal lines 1122 arranged at regular intervals. Next, as shown in FIG. 42B, the first insulating film 1121 in which the signal lines 1122 formed in a lump are arranged in multiple stages with the second insulating film 1123 interposed therebetween, and the outermost layer is externally provided. After the conductor 1124 is laminated, each layer is pressure-bonded.

  Then, as shown in FIG. 42 (C), the multi-core coaxial cable 1130 is cut out by dividing the manufactured laminated body in the vertical direction with a slicer. Finally, as shown in FIG. 42D, the external conductor 1131 is formed on the side surface of the cut multi-core cable 1130. The outer conductor 1131 is connected to each other by contacting the outer conductor 1120 inside the multi-core coaxial cable 1130 on the side of the cable. Thereby, a multi-core coaxial cable is completed.

  Note that according to the manufacturing method shown in FIGS. 42A to 42D, a plurality of multi-core coaxial cables can be cut out at a time, so that the central conductor that can be manufactured at low cost and forms a signal line. Since the structure is completely covered with the outer conductor, it has high noise resistance and can prevent crosstalk between transmission lines.

  However, although the multi-core cable formed by the manufacturing method shown in FIGS. 42A to 42D is excellent in noise resistance, it is difficult to completely eliminate the influence of external noise. Furthermore, although it has excellent noise characteristics, when the signal transmission rate exceeds GHz, external noise becomes a major factor that reduces the reliability of the transmission signal. Even for cables, measures against external noise are indispensable.

  A differential signal transmission method is known as a transmission method that is extremely resistant to external noise. In this system, signals having opposite phases to each other are sent to a pair of signal lines, and the difference between the signals is canceled out. In principle, no external noise is generated.

  FIG. 43 shows a basic configuration of a conventional differential signal transmission cable 1200. As shown in FIG. 43, two signal lines provided with an insulating layer 1202 are arranged in parallel on the outer periphery of an inner conductor 1201 made of a stranded wire of a plurality of conductor strands, and this two-core signal line (twisted pair) An outer conductor 1203 forming a shield layer is surrounded on the outer periphery of the outer periphery of the outer periphery, and a sheath 1204 made of an insulating material is further surrounded on the outer periphery. In order to give a ground potential to the external conductor 1203 that forms the shield layer, the drain line 1205 is disposed so as to contact the external conductor 1203 along the signal line of the twisted pair. For example, Patent Documents 2 to 4 show conventional techniques related to such differential signal transmission using a twisted pair.

  On the other hand, with an increase in signal lines, a cable in which a plurality of differential signal lines (two-core signal lines) are arranged in parallel is realized. FIG. 44 shows an example of a flat type multi-core differential signal transmission cable 1210 in which a plurality of differential signal lines are integrally configured in parallel. This is called a dual strip line, and a plurality of pairs of differential transmission lines composed of conductive wirings 1211 and 1212 formed so as to face each other are embedded in a dielectric layer 1213 in parallel. Shield layers 1214 and 1215 are formed on both surfaces of the layer 1213. If a flexible film is used for the dielectric layer, a flexible differential signal transmission cable (flat cable) can be formed.

  44, an example of a dual strip line in which a pair of conductive wirings are aligned in the vertical direction has been described as the differential signal line. However, a configuration called a so-called microstrip line in which a pair of conductive wirings are arranged in the horizontal direction is described. Can also be adopted. For example, Patent Documents 5 and 6 show conventional techniques related to differential signal transmission using such a multicore flat cable.

  45A to 45E show a method for manufacturing the differential signal transmission cable shown in FIG. In FIG. 45A, a dielectric sheet 1220 having conductive foils 1214 and 1221 formed on both sides is prepared. As shown in FIG. 45B, the conductive foil formed on the top surface of the dielectric sheet 1220 is prepared. A plurality of conductive wirings 1211 are formed by patterning 1221 by etching. Next, as shown in FIG. 45C, after the dielectric layer 1222 and the conductive foil 1223 are formed on the entire surface of the dielectric sheet 1220, the conductive foil 1223 is formed as shown in FIG. A plurality of conductive wirings 1212 are formed by patterning by etching. At this time, the conductive wiring 1212 is aligned with a position facing the conductive wiring 1211 and is formed with the same width as the conductive wiring 1211. As a result, a pair of differential transmission lines with uniform characteristic impedance is configured. Finally, as shown in FIG. 45E, a dielectric layer 1223 and a conductive foil 1215 are formed on the entire surface of the dielectric sheet 1220, so that a plurality of differential transmission lines can be made of a dielectric material (dielectric sheet 1220). And the differential signal transmission cable embedded in the dielectric layers 1222, 1223) is completed.

The differential signal transmission method has a feature that it is resistant to external noise, but in order to transmit the differential signal at a higher speed, the characteristic impedance in the two-core signal line of the differential signal transmission cable is aligned, or It is necessary to take measures such as reducing skew (propagation delay time difference).
JP 2003-323824 A JP 2001-093357 A JP 2002-358841 A JP 2004-087198 A Japanese Patent Application Laid-Open No. 2001-210959 Japanese Patent Application Laid-Open No. 2002-158452

  In the differential signal transmission cable 1200 shown in FIG. 43, the pair of internal conductors 1201 forming a twisted pair is composed of stranded wires of a plurality of conductor strands. There may be tension variations between the lines. Then, the physical lengths of the two-core signal lines forming the twisted pair are varied, which causes an increase in skew.

  As shown in FIG. 43, the drain line 1205 is in contact with the insulating layer 1202 that covers the outer periphery of the pair of internal conductors 1201 forming a twisted pair, but when the twisted pair and the drain line 1205 are surrounded by the external conductor 1203, When the drain line 1205 and the external conductor 1203 are in strong contact with each other, the drain line may bite into the insulating layer 1202 and crush the insulating layer 1202. If it does so, the dispersion | variation in a capacity | capacitance will arise between the signal wires of 2 cores of a differential signal transmission cable, and this will cause the balance of characteristic impedance to be lost.

  In order to solve such a problem, for example, as shown in Patent Document 4, an inclusion is provided between a pair of twisted pair wires in which the inner conductor 1201 is covered with the insulating layer 1202 and the drain wire 1205. It is. However, due to the shape of the inclusions, the distance between the twisted pair wire and the drain wire 1205 is not constant inside the transmission cable 1200, causing a new problem that the balance of characteristic impedance is lost, and a highly reliable differential signal transmission cable. Is difficult to realize.

  On the other hand, in the multi-core differential signal transmission cable 1210 shown in FIG. 44, since the pair of conductive wirings 1211 and 1212 are formed by etching, the wiring width is likely to vary. Since it is formed in alignment with the other conductive wiring 1211, variations in alignment are likely to occur. As a result, these manufacturing variations cause the characteristic impedance of the differential signal transmission cable to be unbalanced. Although it is possible to suppress manufacturing variations by increasing the processing accuracy, this leads to an increase in cost due to the introduction of high-precision processing equipment, and there is a limit to improving processing accuracy for long-distance cables. is there.

  As described above, in the conventional differential signal transmission cable, problems such as variation in characteristic impedance and occurrence of skew occur. These inconveniences cause malfunctions due to deterioration of signal transmission, and hinder speeding up of differential signal transmission.

  The multi-core simultaneous cable formed by the manufacturing method shown in FIGS. 42 (A) to 42 (C) has a stripline structure, but the cut portion shown in FIG. A multi-core differential transmission cable having a pair of signal lines constituting a differential signal transmission line as a unit can be formed by changing to a position including two signal lines arranged in parallel along the line.

  However, in the multi-core differential transmission cable formed in this way, since the pair of signal lines are formed by etching, the width of the signal lines and the interval between the signal lines are likely to vary. Since these values are parameters that determine the characteristic impedance of the differential signal transmission cable, variations in manufacturing of these values directly affect variations in the characteristic impedance of the differential signal transmission cable. The variation in characteristic impedance causes malfunction due to deterioration of signal transmission and becomes a factor that hinders the speedup of differential signal transmission.

  In addition, when a differential signal transmission path is configured by using signal lines formed in different layers (that is, upper and lower layers, such as different layers in the vertical direction) as a pair of signal lines, the pair of signal lines is different. Accurate alignment between layers is difficult and misalignment tends to occur.

  The positional deviation directly affects the variation in the characteristic impedance of the characteristic impedance of the differential signal transmission cable. As a result, the variation in the characteristic impedance causes a malfunction due to the deterioration of signal transmission and becomes a factor that hinders the speeding up of differential signal transmission.

  Therefore, a main object of the present invention is to provide a highly reliable differential transmission cable with less variation in characteristic impedance and less skew.

  In order to solve the above-described problems, the signal transmission cable of the present invention includes a dielectric core layer extending along the longitudinal direction of the cable, a first conductive layer laminated on one surface of the dielectric core layer, A second conductive layer laminated on the other surface of the dielectric core layer; an insulator covering the dielectric core layer and the first and second conductive layers; and a conductivity covering the insulator. A shield layer; and an insulating sheath further covering the conductive shield layer. The dielectric core layer and the first and second conductive layers have the same width. The first and second conductive layers have the same thickness.

  With the above configuration, the transmission core cable constituted by three layers of the first conductive layer, the dielectric core layer, and the second conductive layer has each parameter (the thickness, width, and thickness of each layer) that determines the characteristic impedance of the transmission core cable. Since the value of (interval) can be made uniform, a highly reliable signal transmission cable free from variations in characteristic impedance can be realized.

  The first conductive layer and the second conductive layer preferably constitute a pair of differential signal lines.

  In addition, a first dielectric layer is stacked on the first conductive layer, a first grounding conductive layer is stacked on the first dielectric layer, and the second conductive layer is stacked on the first conductive layer. A second dielectric layer is laminated, and a second grounding conductive layer is laminated on the second dielectric layer, and the first dielectric layer, the first grounding conductive layer, The second dielectric layer and the second grounding conductive layer have the same width as the dielectric core layer, the first conductive layer, and the second conductive layer, and It is preferable that the dielectric layer and the second dielectric layer have the same thickness.

  Furthermore, it is preferable that the thickness of the dielectric core layer is thinner than the thickness of the first and second dielectric layers.

  Note that a plurality of the transmission core cables may be included, and the plurality of transmission core cables may be enclosed in the insulator.

A grounding conductive film may be provided on the other surface of the dielectric sheet.
The dielectric core layer is preferably made of any one of polyimide, wholly aromatic polyamide, polyethylene terephthalate, polyphenylene sulfide, and liquid crystal polymer.

  The first conductive layer and the second conductive layer preferably have different surface colors or shapes.

  Moreover, it is preferable that the thickness of the cable longitudinal direction edge part of the said transmission core cable is thicker than the thickness of another cable area | region.

  The method of manufacturing a signal transmission cable according to the present invention includes a step of preparing a dielectric core sheet having a sheet length equal to or longer than the cable length and a sheet width equal to or wider than a plurality of times of the cable width, and the dielectric A step of laminating a conductor sheet on each side of the body core sheet to cover the both sides, a step of dividing the dielectric core sheet by a cable width and simultaneously forming a plurality of transmission core cables, and the plurality of transmission cores Encasing each of the cables with an insulator.

  In addition, it is preferable that the method further includes a step of removing a residue of the conductive material sheet remaining on a divided section of the transmission core cable after the dielectric core sheet is divided to form a plurality of transmission core cables.

  Another method of manufacturing a signal transmission cable according to the present invention includes a step of preparing a dielectric core sheet having a sheet length equal to or longer than the cable length and a sheet width equal to or wider than a plurality of times the cable width; Laminating a conductor sheet on each of both surfaces of the dielectric core sheet and covering the both surfaces; Laminating a dielectric sheet on each of the conductor sheets and covering the conductor sheet; and each of the dielectric sheets A step of covering the dielectric sheet by laminating a conductor sheet for grounding, a step of dividing the dielectric core sheet by a cable width and simultaneously forming a plurality of transmission core cables, and a plurality of transmission core cables And encapsulating each with an insulator.

  According to the signal transmission cable of the present invention described above and the manufacturing method thereof, each parameter for determining the characteristic impedance of the transmission core cable composed of three layers of the first conductive layer, the dielectric core layer, and the second conductive layer. Since the values of (thickness, width, and interval of each layer) can be made uniform, a highly reliable signal transmission cable without variation in characteristic impedance can be realized. In addition, since the transmission core cable is formed by simultaneously cutting a plurality of transmission core cables after forming the first conductive layer, the dielectric core layer, and the second conductive layer, the transmission core cable has the same characteristics. The signal transmission cable can be manufactured with high yield. Because the color or shape of the surface of the first conductive layer and the second conductive layer is different, the terminals are either the first or second conductive layer at both ends of the transmission cable of the present invention. Or can be easily determined. Thus, the present invention can provide a high-speed and highly reliable signal transmission cable.

  The same effect can be obtained even if the colors and shapes of the first and second dielectric layers are changed.

  The manufacturing method of the multi-core differential transmission cable according to the present invention includes a first dimension having a longitudinal dimension equal to or longer than the longitudinal dimension of the cable and a width dimension equal to or wider than a plurality of dimensions of the cable width direction. A step of forming a laminate sheet by laminating a conductor sheet, a first dielectric sheet, and a second conductor sheet in this order, and a plurality of the laminate sheets are divided into a second dielectric sheet. The step of forming a long sheet by sequentially laminating the sheet, and the step of dividing the long sheet and the cable width along the longitudinal direction of the long sheet are included.

  With the above configuration, a pair of signal lines constituting a differential transmission line is obtained by dividing the laminated sheet composed of the first conductor sheet, the first dielectric sheet, and the second conductor sheet all together. The line width (the width of the cut first and second conductor sheets) and the distance between the signal lines (the thickness of the first dielectric sheet) are formed to be uniform. Therefore, the variation in the characteristic impedance of the differential transmission path can be reduced. In addition, since the long sheet on which the laminate sheet constituting the differential transmission path is laminated is cut at once, the width of the signal line between the plurality of laminated differential transmission paths and the interval between the signal lines Variations can also be reduced. Therefore, a multi-core differential transmission cable with uniform characteristic impedance can be realized.

  In addition, as a pre-process for dividing the long sheet, the process of winding the long sheet into a roll shape, the step of dividing the long sheet from the long sheet wound into a roll shape It is preferable to divide the sheet while pulling out the end of the sheet.

  The multi-core differential transmission cable of the present invention includes a first conductor sheet, a first dielectric sheet, and a first conductor sheet each having a longitudinal dimension equivalent to a longitudinal dimension of the cable and a width dimension equivalent to a dimension of the cable width direction. A laminate sheet obtained by laminating the second conductor sheet in this order is provided. The first conductor sheet and the second conductor sheet have the same thickness. The laminate sheet is obtained by laminating a third dielectric sheet and a third conductor sheet in this order on at least one surface of the first and second conductor sheets. A plurality of the laminate sheets are sequentially laminated with a second dielectric sheet interposed. The first conductor sheet and the second conductor sheet constitute a pair of differential transmission lines arranged with the first dielectric sheet interposed therebetween. The third conductor sheet constitutes a ground wire.

  In addition, the connector is provided in the cable edge part, and it is preferable that the said connector has a thick part from which the thickness of a said 2nd dielectric sheet is thicker than another sheet | seat site | part. In this case, it is preferable that a part of the second dielectric sheet in the thick portion is deleted and the first and second conductor sheets are exposed.

  The multi-core differential transmission cable and the method for manufacturing the same according to the present invention are obtained by dividing a laminated sheet composed of a first conductor sheet, a first dielectric sheet, and a second conductor sheet in a lump. The line width of the pair of signal lines constituting the differential transmission path (the width of the cut first and second conductor sheets) and the distance between the signal lines (the thickness of the first dielectric sheet) are uniform. Formed. Therefore, the variation in the characteristic impedance of the differential transmission path can be reduced. In addition, since the long sheet on which the laminate sheet constituting the differential transmission path is laminated is cut at once, the width of the signal line between the plurality of laminated differential transmission paths and the interval between the signal lines Variations can also be reduced. Therefore, a multi-core differential transmission cable with uniform characteristic impedance can be realized.

  Furthermore, since a plurality of multi-core differential transmission cables can be manufactured at the same time by dividing the long sheet on which the laminate sheet is laminated, an inexpensive multi-core differential transmission cable can be realized. Can do.

  The method for producing a flexible differential transmission cable of the present invention includes a step of forming a first conductive film on a flexible dielectric sheet, a step of forming a dielectric film on the first conductive film, Forming a second conductive film on the dielectric film; and cutting the second conductive film, the dielectric film, and the first conductive film to form a plurality of strip-shaped grooves in the dielectric A differential transmission line comprising a laminate of the first conductive film, the dielectric film, and the second conductive film formed in parallel on the sheet and separated by the groove portions between the adjacent groove portions. And a step of embedding an insulator in the groove after forming the differential transmission line. The groove portions are formed to have the same width, and the differential transmission line is configured by the stacked body having the same width.

  It is preferable that the method further includes a step of covering the groove embedded with the insulator and the differential transmission line with an insulating layer.

  The method for manufacturing a flexible differential transmission cable of the present invention preferably further includes a step of forming a ground layer on the insulating layer.

  The method for manufacturing a flexible differential transmission cable according to the present invention preferably includes a step of forming a ground layer on the back surface of the dielectric sheet.

  In the flexible differential transmission cable manufacturing method of the present invention, the step of forming the groove may be performed in the thickness direction of the second conductive film, the dielectric film, and the first conductive film. It is preferably performed by cutting halfway to leave a part of the first conductive film to form a strip-shaped groove, and then removing the remaining part of the first conductive film by etching.

  The method of manufacturing a flexible differential transmission cable according to the present invention cuts the first conductive film, the dielectric film, and the second conductive film formed on the dielectric sheet while leaving the dielectric sheet. A plurality of differential transmission lines made of a laminate of the first conductive film, the dielectric film, and the second conductive film separated from each other by forming the belt-shaped groove portion are formed on the dielectric sheet. And a flexible differential transmission cable with high productivity can be realized.

  In addition, the first conductive film, the dielectric film, and the second conductive film are stacked and then simultaneously cut, whereby the first conductive film, the dielectric film, and the second conductive film are stacked. Since the width of the differential transmission line made of a body is determined, the line width of the pair of signal lines constituting the differential transmission line (the width of the cut first and second conductive films) and the distance between the signal lines ( That is, the distance between the first and second conductive films (in other words, the thickness of the dielectric film) and the position of the signal line (alignment of the first and second conductive films) are formed to be uniform. Therefore, variation in characteristic impedance of the differential transmission line can be reduced, and a highly reliable flexible differential transmission cable can be realized.

  Furthermore, by forming the laminated body constituting the differential transmission line with the same width and the same interval, a multi-core differential transmission cable with uniform characteristic impedance can be realized, A flexible differential transmission cable corresponding to a large capacity of data can be realized.

  Therefore, according to the present invention, it is possible to provide a method for manufacturing a flexible differential transmission cable with little variation in characteristic impedance and high productivity.

  In the method for manufacturing a signal transmission cable according to the present invention, a conductor sheet and an insulator sheet are alternately laminated to form a laminate sheet, and the conductive sheet is formed on one sheet surface of the sheet end portion of the laminate sheet. By arranging the end of the body sheet and the end of the insulator sheet in a step-like manner so that the sheet located on the other sheet surface side is closer to the sheet end, A first step of forming a stepped surface on the sheet surface, a second step of bringing a resin member into contact with the other sheet surface of the sheet end of the laminate sheet, and the resin member along the sheet thickness direction. By pressing the step, the end portion of the sheet is deformed so that the staircase surface is flush with the one sheet surface, so that it is exposed to the staircase surface that is flush with the one sheet surface. The conductor sheet From Re respectively and a third step which constitutes the electrode terminals.

  As the resin member, when the resin member is brought into contact with the other sheet surface, the other surface of the resin member located on the opposite side of the one surface of the resin member that comes into contact with the other sheet surface. However, in the third step, the other surface of the resin member is flush with the other sheet surface of the laminate sheet in the third step. It is preferable to deform the sheet end.

  Further, it is preferable that the method further includes a step of configuring the resin member from a semi-cured resin and, after the third step, curing the resin member to integrate the resin member and the laminate sheet.

  Moreover, it is preferable to use what has a magnitude | size which contact | abuts to the whole surface of the said laminated body sheet as said resin member.

  In the third step, it is preferable that the resin member is pressed along the sheet thickness direction in a state where a flat plate is brought into contact with the one sheet surface of the sheet end portion of the laminate sheet.

  The signal transmission cable manufacturing method of the present invention is capable of forming a signal transmission cable having a high-density signal line, and providing an electrode terminal for taking out the signal line of each conductor sheet on its exposed surface, thereby providing another circuit board. Etc. can be easily connected to the terminal.

  Furthermore, since the electrode terminals of each signal line can be arranged in the same plane as the surface of the laminate sheet, a conventional connector can be used for terminal connection with other circuit boards and the like, and the cost can be reduced. it can.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of simplicity. In addition, this invention is not limited to the following embodiment.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing the configuration of the signal transmission cable 100 according to the first embodiment of the present invention. FIG. 2 is a process cross-sectional view illustrating the method for manufacturing the signal transmission cable 100 according to the first embodiment.

  As shown in FIG. 1, the signal transmission cable 100 is laminated on the dielectric core layer 10 extending along the longitudinal direction of the cable (direction orthogonal to the drawing) and on both surfaces of the dielectric core layer 10. It has the transmission core cable 20 with which the 1st conductive layer 11 and the 2nd conductive layer 12 were comprised integrally, and the insulator 13 which encloses this transmission core cable 20. FIG.

  The first conductive layer 11 and the second conductive layer 12 have the same thickness, and the dielectric core layer 10, the first conductive layer 11, and the second conductive layer 12 have the same width. Have Furthermore, the insulator 13 that encloses the transmission core cable 20 is covered with a shield layer 14 made of a conductor, and the shield layer 14 is covered with a sheath 15 made of an insulator. The first conductive layer 11 and the second conductive layer 12 constitute a pair of differential signal lines.

  The characteristic impedance of the pair of differential signal lines is determined by the width of the first and second conductive layers 11 and 12 and the distance between the first and second conductive layers 11 and 12. Therefore, the dimensions of the first and second conductive layers 11 and 12 are determined so that a predetermined characteristic impedance is obtained. For example, the first and second conductive layers 11 and 12 are made of copper, the width is 150 μm, the distance between the first and second conductive layers 11 and 12 is 190 μm, and the dielectric of the dielectric core layer 10 If the ratio is 4.0, a characteristic impedance of about 100Ω can be obtained.

  Next, a method for manufacturing the signal transmission cable 100 according to the first embodiment will be described with reference to FIG. First, as shown in FIG. 2A, a dielectric core sheet 10 'is prepared. Here, a dielectric core sheet 10 ′ is prepared in which an adhesive of about 45 μm is formed on both sides of a polyimide sheet having a thickness of about 100 μm. Here, the dielectric core sheet 10 ′ has a rectangular flat plate shape having a longitudinal direction in the drawing orthogonal direction in FIG. 2A and a width direction in the horizontal direction in the drawing. Furthermore, the dielectric core layer 10 ′ has a longitudinal dimension that is the same as the cable length with the transmission core cable 20, and a width dimension that is equal to or multiple of the cable width of the transmission core cable 20. Use a larger shape.

  Then, as shown in FIG. 2 (B), first and second conductor sheets 11 'and 12' are laminated on the entire surfaces of both surfaces of the dielectric core sheet 10 '. Here, first to second conductor sheets 11 ′ and 12 ′ made of rolled copper foil having a thickness of about 8 μm are prepared, and these first and second conductor sheets 11 ′ and 12 ′ are dielectrically bonded by pressure bonding. Laminate on both sides of the body core sheet 10 '. At this time, only the surface of the first conductor sheet 11 'is colored with a dye. Alternatively, the surface of the first conductor sheet 11 'is roughened. This makes the surface state of the first conductor sheet 11 'different from the surface state of the second conductor sheet 12' in appearance.

  Next, as shown in FIG. 2 (C), the dielectric core sheet 10 ′ having the conductor sheets 11 ′ and 12 ′ formed on both sides is arranged along the longitudinal direction of the sheet for each cable width (for example, 150 μm). Divide into In order to enable such division, the width of the dielectric core sheet 10 'is set to be equal to or larger than a plurality of times of the cable width.

  Thereby, a plurality of transmission core cables 20 having the same width dimension (for example, 150 μm) and continuous in the longitudinal direction are formed simultaneously. The formed transmission core cable 20 has a three-layer structure including the first conductive layer 11, the dielectric core layer 10, and the second conductive layer 12.

  The cutting is performed using a slicer. However, since the copper foil used as the first and second conductive layers 11 and 12 is soft, a copper foil residue may remain on the divided cross section of the transmission core cable 20. There is sex. Since the dielectric core sheet 10 'is very thin, the copper foil residue causes a short circuit between the pair of differential signal lines. Therefore, it is preferable to include a step of removing the residue after the division in order to prevent a decrease in yield. For example, if dip etching is performed with a solution for etching copper, the residue can be removed without affecting the shape of the copper foil after the division. Further, if the cutting is performed using a laser instead of the division by the slicer, the generation of the residue can be suppressed.

  Finally, as shown in FIG. 2 (D), the entire circumference of the transmission core cable 20 cut out by cutting is covered with an insulator 13 having a thickness of about 500 μm, and then the insulator 13 is further shielded by a shield layer having a thickness of about 50 μm. 14 Further, the shield layer 14 is covered with a sheath 15. Thereby, the signal transmission cable 100 is completed.

  Here, as the insulator 13, for example, a fluorine resin such as FEP (tetrafluoroethylene-hexafluoropropylene copolymer resin), an amorphous polyolefin resin, PEN (polyethylene naphthalate), or the like is used. In order to reduce the rate, it is preferable to use a foamed shape containing a foaming agent. As the shield layer 14, a metal tape or metal foil excellent in electrical conductivity such as copper or aluminum, or a metal laminate film obtained by laminating these with a plastic film can be used. For the sheath 15, polyvinyl chloride, polyolefin, or the like can be used.

  In the signal transmission cable 100 formed by such a manufacturing method, the width of the first conductive layer 11 and the width of the second conductive layer 12 constituting the differential signal line can be set to each other without applying a special width adjustment process. A uniform structure can be obtained. In addition, since the dielectric core layer 10 having a certain thickness is inserted between the first and second conductive layers 11 and 12, the distance between the conductive layers 11 and 12 can be set by a special width adjustment process. It is possible to make a structure with the entire length without adding.

  For the above reasons, the characteristic impedance of the signal transmission cable 100 can be accurately maintained at a constant value along the longitudinal direction of the cable. Therefore, the balance of the characteristic impedance of the signal transmission cable 100 is maintained without breaking.

  In addition, since the signal transmission cable 100 is formed by dividing the single dielectric core sheet 10 ′ having both ends aligned in the longitudinal direction, the signal transmission cable 100 cut out from the same dielectric core sheet 10 ′ is formed. The cable physical lengths are aligned with each other, and the occurrence of skew (propagation delay time difference) between these cables is also suppressed.

  Furthermore, even if a large number of signal transmission cables 100 are simultaneously formed from the same dielectric core sheet 10 ', variations in their respective characteristic impedances can be suppressed to a small level. Can be manufactured.

  In the above description, specific materials of each component of the signal transmission cable are exemplified, but the present invention is not particularly limited thereto. For example, the dielectric core layer 10 may be made of wholly aromatic polyamide, polyethylene terephthalate, polyphenylene sulfide, liquid crystal polymer, or the like. Further, the first and second conductive layers 11 and 12 may be an alloy containing copper or other metals.

  The signal transmission cable 100 shown in FIG. 1 shows the basic configuration of the present invention. However, in actual use, it is effective to shield the transmission core cable 20 from the outside. FIG. 3 shows a configuration example of the signal transmission cable 110 having a shielding effect.

  In FIG. 3, the transmission core cable 20 has the same configuration as that in FIG. 1, but the entire circumference of the transmission core cable 20 is covered with an insulating layer 30. Further, a drain line 31 is disposed between the insulating layer 30 and the shield layer 14. The drain line 31 is set to the same length as the signal transmission cable 100. Thereby, the ground potential can be connected to the shield layer 14 via the drain line 31 by connecting the drain line 31 to the ground potential outside the cable. Note that the drain line 31 is press-fitted and disposed in the gap between the insulating layer 30 and the shield layer 14 in order to improve the electrical connectivity between the drain line 31 and the shield layer 14.

  However, the drain line 31 is press-fitted into the gap between the insulating layer 30 and the shield layer 14 with a pressing force that does not collapse the dielectric core layer 10 between the first and second conductive layers 11 and 12. Be placed. Therefore, the provision of the drain line 31 does not cause a problem that the dielectric core layer 10 is deformed and the balance of characteristic impedance is lost.

  Further, the signal transmission cable 100 is also suitable for a multi-core signal transmission cable used when transmitting a plurality of signals in parallel because variations in characteristic impedance among individual transmission signal cables are small.

  FIG. 4 shows a configuration example of a multi-core signal transmission cable 120 in which a plurality of transmission core cables 20 are assembled. In FIG. 4, the plurality of transmission core cables 20 are covered with an insulating layer 13 in a state of being arranged in parallel with each other. Further, the peripheral surface of the insulating layer 13 is covered with the shield layer 14 and the sheath 15. Although FIG. 4 shows an example in which two transmission core cables 20 are arranged in parallel, the number of transmission core cables 20 to be arranged may be increased or decreased according to the number of signals to be transmitted in parallel. Further, the transmission core cable 20 may be covered with the insulating layer 13 not only in a state of being arranged in parallel (arranged in the cable width direction) but also in a state of being arranged in a row (arranged in the cable thickness direction).

(Embodiment 2)
The differential signal line is characterized by being resistant to external noise. However, since the external noise cannot be completely eliminated, the transmission core cable 20 is covered with the shield layer 14 in order to transmit the differential signal more stably. It is preferable to adopt the configuration described above. However, as shown in FIG. 3, in order to apply a ground potential to the shield layer 14, a drain line 31 is newly provided and the shield layer 14 is connected to the ground potential via the drain line 31. Necessary. Such a configuration requires an additional configuration, which complicates the manufacturing process and increases costs.

  FIG. 5 shows a configuration of a signal transmission cable 130 according to the second embodiment of the present invention. In the second embodiment, the shielding effect of the differential signal line is obtained without adding the drain line. In other words, the first and second conductive layers 11 and 12 constituting the pair of differential signal lines are arranged to face each other, and the dielectric core layer 10 is interposed between the conductive layers 11 and 12. These configurations are basically the same as those of the transmission core cable 20 in the first embodiment.

  A first dielectric layer 16 is laminated on the upper surface of the first conductive layer 11, and the upper surface of the first conductive layer 11 is covered with the first dielectric layer 16. Further, a first grounding conductive layer 18 is laminated on the upper surface of the first dielectric layer 16, and the upper surface of the first dielectric layer 16 is covered with the first grounding conductive layer 18. Similarly, the second dielectric layer 17 is laminated on the upper surface of the second conductive layer 12, and the upper surface of the second conductive layer 12 is covered with the second dielectric layer 17. Further, a second grounding conductive layer 19 is laminated on the upper surface of the second dielectric layer 17, and the second dielectric layer 17 is covered with the second grounding conductive layer 19.

  The first and second dielectric layers 16 and 17 have the same thickness, and the first and second dielectric layers 16 and 17 and the first and second grounding conductive layers. 18 and 19 have the same width as the dielectric core layer 10 and the first and second conductive layers 11 and 12, respectively.

  As described above, in the second embodiment, the second grounding conductive layer 19, the second dielectric layer 17, the second conductive layer 12, the dielectric core layer 10, and the first conductive are sequentially arranged from the bottom in the figure. The layer 11, the first dielectric layer 16, and the first grounding conductive layer 18 are stacked, thereby forming the transmission core cable 21.

  The characteristic impedance of the pair of differential signal lines configured as shown in FIG. 5 is affected by the widths of the first and second conductive layers 11 and 12 and the spacing between the first and second conductive layers 11 and 12. receive. In addition, the characteristic impedance is affected by the separation distance between the first or second conductive layer 11, 12 and the first or second grounding conductive layer 18, 19. The characteristic impedance is defined by adjusting them. Therefore, in the transmission core cable 21, the dimensions of the respective constituent elements are set so that a desired characteristic impedance is obtained.

  For example, in this case, the dielectric core layer 10 is made of a polyimide sheet, the first and second conductive layers 11 and 12 are made of rolled copper foil, and the first and second dielectric layers 16 and 17 are made of polyimide. The first and second grounding conductive layers 18 and 19 are made of rolled copper foil, and the first and second conductive layers 11 and 12 have a width of 135 μm and the first and second conductive layers 18 and 19 are made of a sheet. The distance between the conductive layers 11 and 12 is 190 μm, and the distance between the first or second conductive layers 11 and 12 and the first or second grounding conductive layers 18 and 19 is 250 μm. Then, a characteristic impedance of about 100Ω can be obtained.

  With the above configuration, since the pair of differential signal lines 11 and 12 are covered with the ground layers 18 and 19 on both surfaces, a shield effect can be effectively provided to these differential signal lines. In this case, since both the ground layers 18 and 19 can be directly connected to the ground potential outside the cable, there is no need to newly provide a drain line, and the configuration is simplified correspondingly.

  The dielectric core layer 10 is thinner than the first and second dielectric layers 16 and 17. As a result, the coupling of the differential signal lines is strengthened, and the signal quality is improved.

  Next, a method for manufacturing the signal transmission cable 130 according to the second embodiment will be described with reference to FIGS. 6 (A) to 6 (D).

  First, as shown in FIG. 6A, a laminate in which first and second conductor sheets 11 'and 12' are laminated on both surfaces of a dielectric core sheet 10 'is prepared. Here, a dielectric core sheet 10 ′ is prepared in which an adhesive of about 45 μm is formed on both sides of a polyimide having a thickness of about 100 μm. Here, the dielectric core sheet 10 ′ has a rectangular flat plate shape in which the thickness direction in FIG. 6A is the longitudinal direction and the left-right direction is the width direction. Furthermore, the dielectric core layer 10 ′ has a longitudinal direction with a sheet length dimension equivalent to the cable length and a sheet width dimension that is a multiple of the cable width.

  The first and second conductor sheets 11 ′ and 12 ′ are laminated on the entire surfaces of both surfaces of the dielectric core sheet 10 ′ to cover the dielectric core sheet 10 ′. Here, first to second conductor sheets 11 ′ and 12 ′ made of rolled copper foil having a thickness of about 8 μm are prepared, and these first and second conductor sheets 11 ′ and 12 ′ are dielectrically bonded by pressure bonding. Laminate on both sides of the body core sheet 10 '. At this time, the surface of the first conductor sheet 11 'is colored with a dye.

  Next, as shown in FIG. 6B, the first and second dielectric sheets 16 ′ and 17 ′ are laminated on the entire upper surface of the first and second conductor sheets 11 ′ and 12 ′. Further, first and second ground sheets 18 ′ and 19 ′ are laminated on the entire upper surface of the first and second dielectric sheets 16 ′ and 17 ′. The first and second dielectric sheets 16 ′ and 17 ′ are made of a polyimide film having a thickness of about 170 μm, and the first and second ground sheets 18 ′ and 19 ′ are a rolled copper foil of about 8 μm. Consists of

  As shown in FIG. 6C, the laminated dielectric core sheet 10 'is divided for each cable width along the sheet longitudinal direction. Thereby, the several transmission core cable 21 which has the same cable width is formed simultaneously.

  The total thickness of the transmission core cable 21 to be formed is about 570 μm, but if this thickness is about this, it can be easily cut with a general-purpose slicer (not shown). Note that, as described in the manufacturing process shown in FIG. 2, since a copper foil residue may be generated in the divided cross section of the transmission core cable 21, it is preferable to include a predetermined process for removing the residue after the division. .

  Finally, as shown in FIG. 6D, the transmission core cable 21 cut out by cutting is encapsulated with an insulator 13, and if necessary, covered with a sheath 15 to complete the signal transmission cable 130. Let As the insulator 13, PEN containing a foaming agent is used, and the sheath 15 is made of polyvinyl chloride.

(Embodiment 3)
7 and 8 show the configuration of the signal transmission cables 140 and 150 according to Embodiment 3 of the present invention.

  FIG. 7 shows a so-called multi-core flat cable in which a plurality of transmission core cables 20 are assembled, and has a single dielectric sheet 40, and a plurality of dielectric sheets 40 are formed on one surface of the dielectric sheet 40. The transmission core cables 20 (the same configuration as that described in the first embodiment) are arranged in parallel at substantially equal intervals. An insulating sheet 41 that covers the transmission core cable 20 is laminated on one surface of the dielectric sheet 40. Since the transmission core cable 20 is arranged, the dielectric sheet 40 has a longitudinal dimension equivalent to the cable length dimension of the transmission core cable 20 and a width dimension in which the plurality of transmission core cables 20 are arranged in parallel. Have

  The dielectric sheet 40 uses a polyimide sheet having a thickness of about 150 μm on which both sides of an adhesive of about 75 μm are formed. The dielectric sheet 40 is heated while the insulating sheet 41 made of PEN containing a foaming agent is heated by a laminating method. Crimp to.

  The transmission core cable 20 manufactured in the manufacturing process described with reference to FIG. 2 is formed so that the widths of the first and second conductive layers 11 and 12 constituting the pair of differential signal lines are uniform. Since the thickness of the dielectric core layer 10 inserted between the first and second conductive layers 11 and 12 is also constant, the characteristic characteristic impedance of the differential signal line is a constant value along the transmission core cable 20. Can keep. Further, since the cable end portion of the transmission core cable 20 is also collectively cut in the state of the dielectric core sheet 10 ′, the physical length of the cable is also formed so that the occurrence of skew is suppressed. Furthermore, since a large number of transmission core cables 20 are formed simultaneously from a single dielectric core sheet 10 ', variations in the characteristic impedance of each transmission core cable 20 are small. Therefore, the multi-core signal transmission cable of the present embodiment formed by placing a plurality of transmission core cables 20 manufactured in this way in parallel is highly reliable with uniform characteristic impedance. Thus, the structure of the present invention is suitable for a signal transmission cable for high-speed parallel transmission.

  FIG. 8 is a diagram illustrating a configuration of the signal transmission cable 150 in which the signal transmission cable 140 illustrated in FIG. 7 is provided with a shielding effect.

  As shown in FIG. 8, the signal transmission cable 150 has a cable configuration equivalent to that of the signal transmission cable 140, and further, both surfaces of the cable configuration (signal transmission cable 140) (on the outer surface of the insulating sheet 41 and Grounding conductive films 42 and 43 are formed on the entire outer surface (the other surface) of the dielectric sheet 40. Further, the outer surfaces of the grounding conductive films 42 and 43 are covered with sheaths 44 and 45, respectively.

  If the grounding conductive films 42 and 43 are connected to the ground potential, the grounding conductive films 42 and 43 function as a shield layer. Here, the grounding conductive films 42 and 43 are arranged at a certain distance above and below the transmission core cable 20 arranged in parallel (on both sides in the cable thickness direction). A stable shielding effect can be exhibited.

  In the above description, the grounding conductive films 42 and 43 are provided on both surfaces of the dielectric sheet 41 to obtain a necessary and sufficient shielding effect. However, at least the insulating sheath on which the transmission core cable 20 is not laminated is obtained. If a conductive film for grounding is provided on the other surface of the G 41, a shielding effect can be obtained.

(Embodiment 4)
Next, a method for manufacturing a signal transmission cable according to Embodiment 4 of the present invention will be described with reference to FIGS. 9 (A) to 9 (E), FIG. 10 (A), and FIG. 10 (B).

  9A to 9E are process cross-sectional views illustrating a method for manufacturing the signal transmission cable 160. First, as shown in FIG. 9A, a dielectric core sheet 10 'is prepared by laminating first and second conductor sheets 11' and 12 'on both surfaces.

  Next, as shown in FIG. 9B, the dielectric core sheet 10 ′ is divided into fixed widths (cable widths) along the longitudinal direction of the sheet (the direction perpendicular to the paper surface). As a result, a plurality of transmission core cables 20 having the same cable width and having a three-layer structure of the first conductive layer 11, the dielectric core layer 10, and the second conductive layer 12 are simultaneously formed. The configuration of the transmission core cable 20 and the manufacturing method thereof are the same as the structure of the transmission core cable 20 and the manufacturing method thereof described in the first embodiment.

  Next, as shown in FIG. 9C, a first dielectric sheet 50 having a sheet size on which a plurality of transmission core cables 20 arranged in parallel can be placed is prepared. The transmission core cables 20 are arranged in parallel on the body sheet 50 at a certain interval.

  Next, as shown in FIG. 9D, a second dielectric sheet 51 having a size equivalent to that of the first dielectric sheet 50 is prepared, and the upper surface (first dielectric body) of the transmission cable 20 is prepared. The second dielectric sheet 51 is placed so as to be in contact with the surface not in contact with the sheet 50. As a result, the plurality of transmission core cables 20 are covered with the second dielectric sheet 51. Further, the first and second dielectric sheets 50 and 51 are divided from the direction of the arrow (the thickness direction of the transmission core cable 20). In that case, it divides | segments along the cable longitudinal direction of the transmission core cable 20, and let the division | segmentation position be a position where the cable between the adjacent transmission core cables 20 does not exist.

  Finally, as shown in FIG. 9 (E), the cut ends of the first and second dielectric sheets 50 and 51 are bonded to each other to join them together. In addition, the transmission core cables 20 are covered with the integrated dielectric sheets 50 and 51. Thereby, the signal transmission cable 160 covered with the first and second dielectric sheets 50 and 51 is completed.

  As the dielectric sheet, it is preferable to use polyvinyl chloride, polyethylene, or the like that has excellent bondability by pressure bonding.

  In the signal transmission cable manufacturing method according to the fourth embodiment, a large number of signal transmission cables can be formed simultaneously through a series of simple steps, and therefore a signal transmission cable with a constant quality with little variation in characteristics can be manufactured. In addition, since the number of processes is small, the signal transmission cable can be manufactured at low cost.

  10A and 10B are process cross-sectional views illustrating the method for manufacturing the signal transmission cable 170. FIG. FIG. 10A is a cross-sectional view shown in FIGS. 9A to 9E until the transmission core cable 20 is covered with the first and second dielectric sheets 50 and 51. FIG. The state (FIG. 9D) is shown. Here, the first dielectric sheet 50 and the second dielectric sheets 50 and 51 are not divided.

  Next, as shown in FIG. 10 (A), the first along the cable longitudinal direction of the transmission core cable 20 and the position where the transmission core cable 20 is not disposed (between adjacent transmission core cables 20). The first and second dielectric sheets 50 and 51 are joined to each other without being separated by crimping the second and second dielectric sheets 50 and 51 along the direction of the arrow (cable thickness direction). Let

  FIG. 10 (B) is a diagram showing a state after crimping. The signal transmission cable 170 is sealed inside the dielectric sheets 50 and 51 integrated with each other, and further the signal transmission cable. 170 is housed inside the dielectric sheets 50 and 51 in a state where they are separated along the longitudinal direction of the cable by the joint portions of the dielectric sheets 50 and 51, so to speak, it looks like a hook-like connection. ing.

  Thereby, each transmission core cable 20 is firmly fixed by the dielectric sheet, and each transmission core cable 20 is connected in a bowl shape, so that it can be used as a flexible multi-core signal transmission cable. In FIGS. 9 and 10, it is preferable to provide a grounding layer outside the first and second dielectric sheets 50 and 51 because a high shielding effect can be obtained.

(Embodiment 5)
The signal transmission cable 20 of the present invention preferably has a connector structure suitable for coupling with a connection partner side at the end of the cable. The signal transmission cable of the present invention having a connector structure at the cable end will be described with reference to FIGS. 11 and 12 are cross-sectional views in which the transmission core cable 20 is sectioned along the cable longitudinal direction, and FIG. 1 is a diagram in which the transmission core cable 20 is sectioned along the cable width direction. Different from FIG.

  As shown in FIG. 11, in the transmission core cable 20, the thickness of the dielectric core layers 10a and 10b at both ends in the cable longitudinal direction is thicker than the thickness of the dielectric core layer 10 in other regions. Hereinafter, the thick cable ends are referred to as connector structures 10a and 10b. Such a configuration is, for example, as a pretreatment for forming the first and second conductive layers 11 and 12, along the cable width direction at both ends of the transmission core cable 20 in the cable longitudinal direction on both surfaces of the dielectric core layer 10. Thus, it can be easily formed by selectively laminating additional dielectric layers. In FIG. 11, the insulator 13 of the transmission core cable 20 is not shown.

  FIG. 12 shows the configuration of the connector 60 on the connection partner side of the transmission core cable 20 formed in this way. The covering of the insulator 13 and the like is removed at the cable end of the signal transmission cable 20, and the connector structures 10a and 10b are exposed. On the other hand, the end portion of the connector 60 becomes a conductive clip 61 which is conductive.

  Therefore, the transmission core cable 20 can be easily and surely connected to the connector 60 by sandwiching the clip 61 of the connector 60 between the connector structures 10 a and 10 b of the signal transmission cable 20. Here, the first and second conductive layers 11 and 12 are colored in different colors, or part of their shapes are different from each other.

  In the configuration of the signal transmission cable of the present invention, it is necessary to make the first and second conductive layers 11 and 12 clearly distinguishable. Otherwise, when the signal transmission cable is connected to another electrical part, the other electrical part may be connected to a conductive layer different from the conductive layer to be connected, and signal transmission may not be possible. There is.

  In each of the embodiments of the present invention described above, the first and second conductive layers 11 and 12 are colored and colored, or part of the shapes thereof are different from each other, so that the first and second conductive layers 11 and 12 are colored. The layers 11 and 12 are configured to be clearly distinguishable. The color coding is performed as follows, for example.

(First color-coded structure)
By forming irregularities on the surfaces of the first and second conductive layers 11 and 12, respectively, and further changing the shape of the irregularities (irregular patterns) between the conductive layers, the brightness and brightness are different. Color code. For example, when the first and second conductive layers 11 and 12 are made of electrolytic copper foil, a shiny surface (glossy surface) and a matte surface (rough surface) are formed on the surface of the conductive layer due to the manufacturing method of the copper foil. Is done. The shiny surface and the mat surface are different in color to the extent that they can be distinguished visually. Specifically, the shiny surface becomes a mirror surface and reflects light, and the matte surface has a dull color. Taking advantage of such characteristics, one of the first and second conductive layers 11 and 12 is used as a shiny surface, and the other is used as a matte surface, so that both surfaces are color-coded.

(Second color-coded structure)
When the 1st, 2nd conductive layers 11 and 12 are comprised from a rolled copper foil, the said color classification cannot be implemented. Therefore, when the first and second conductive layers 11 and 12 are formed from rolled copper foil, for example, the surface of one of the conductive layers is scratched, or the copper foil that becomes one of the conductive layers is stretched. A roller having irregularities formed on the surface thereof is selectively used. Then, the surface shape of one of the formed conductive layers can be made to be a shape different from the other when viewed visually.

(Third color-coded structure)
The surface of the first and second conductive layers 11 and 12 is colored with a pigment or dye.

(Fourth color coding structure)
The first and second conductive layers 11 and 12 (first and second conductor sheets 11 ′ and 12 ′) are formed on the dielectric core layer 10 (dielectric core sheet 10 ′) by plating or vapor deposition of a conductive material. ) And the first and second conductive layers 11 and 12 (first and second conductive sheets 11 ′ and 12 ′) are made different from each other in the formation method. Use different shapes.

(Fifth color coding structure)
By selectively etching one of the surfaces of the first and second conductive layers 11 and 12, the surface shape is visually different from that of the other.

  In addition to color coding, the first and second conductive layers 11 and 12 may have different shapes. For example, as shown in FIG. 13, a notch α is selectively formed only at the corner of one end of the first and second conductive layers 11 and 12. Moreover, as shown in FIG. 14, a hole or a dent is selectively formed only in one end portion of the first and second conductive layers 11 and 12. In FIG. 14A, a circular hole or recess β is formed at one end of the first and second conductive layers 11 and 12, and in FIG. 14B, the first and second conductive layers 11 and 12 are formed. A wedge-shaped recess γ is formed at the edge of one end of the conductive layers 11 and 12.

  In this way, the first and second conductive layers 11 and 12 are colored by coloring, or part of their shapes are made different from each other, so that the first and second conductive layers 11 and 12 are made different from each other. It is possible to easily determine the connection direction with a clearly distinguishable configuration.

(Embodiment 6)
FIGS. 15A, 15B, and 16 are process diagrams showing a method of manufacturing a multicore differential transmission cable according to Embodiment 6 of the present invention.

  First, as shown in FIG. 15A, a plurality of laminate sheets A in which a first conductor sheet 210, a first dielectric sheet 211, and a second conductor sheet 212 are sequentially laminated are prepared. Thereafter, the laminate sheet A is sequentially laminated with the second dielectric sheet 213 interposed therebetween, and the respective layers are pressure-bonded to form the long sheet 220 shown in FIG. The longitudinal dimension L of the formed long sheet 220 is equivalent to the longitudinal dimension of the multi-core differential transmission cable to be produced, and the width dimension W1 is equivalent to a plurality of times the width dimension of the multi-core differential transmission cable to be produced. Or make it bigger. In order to form the long sheet 220 having such a size, the shapes of the first and second conductive sheets 210 and 212 and the first and second dielectric sheets 211 and 213 are set.

  Next, as shown in FIG. 16, along the longitudinal direction (direction perpendicular to the drawing plane) of the long sheet 220 on which the laminate sheet A is laminated, for each cable width W2 indicated by a dotted line. Divide. FIGS. 17A and 17B are cross-sectional views of the long sheet 220 along its width direction.

  Here, the first conductor sheet 210 and the second conductor sheet 212 form a pair of differential transmission lines sandwiched between the first dielectric sheet 211 and the long sheet 220. A plurality of multi-core differential transmission cables 221 can be cut out by dividing them together.

  FIG. 17A is a cross-sectional view of one cut multi-core differential transmission cable 221 along its width direction, and FIG. 17B is one of the multi-core differential transmission cables 221. It is the principal part expanded sectional view which expanded the part which comprises this differential transmission path. 17 (A) and 17 (B), the multi-core differential transmission cable 221 extends in the vertical direction of the drawings. Hereinafter, in these drawings, the first and second conductor sheets 210 and 212 are shown. A direction along the thickness direction (left and right direction in the drawing) is referred to as a cable height direction of the multi-core differential transmission cable 221. In these drawings, the planar direction (longitudinal direction) of the first and second conductor sheets 210 and 212 is shown. The direction along the direction (not the direction) is the cable width direction W2 of the multicore differential transmission cable 221.

  The characteristic impedance of the pair of differential transmission lines constituted by the first and second conductor sheets 210 and 212 is a ratio h / W2 (h is a separation interval between transmission lines constituting the pair of differential transmission lines, W2 is proportional to the width of the differential transmission path). Here, h is determined by the initial thickness of the first dielectric sheet 211, and W2 is determined by the dividing width of the long sheet 220. Therefore, variation in characteristic impedance in the multicore differential transmission cable 221 is very small.

  The first and second conductor sheets 210 and 212 are made of rolled copper foil having the same thickness (for example, 8 μm). The first dielectric sheet 211 is a fully aromatic aramid film in a prepreg state having a predetermined thickness (for example, 30 μm), and the second dielectric sheet 213 has a predetermined thickness (for example, 60 μm). A prepreg state polyimide film is used. The second dielectric sheet 213 needs to be thicker than the first dielectric sheet 211 because it is necessary to insulate and separate the differential transmission paths (first and second conductor sheets 210 and 212). It is preferable.

  18A and 18B show a configuration in which the multi-core differential transmission cable 221 is shielded. As shown in FIG. 18A, both surfaces 221a of the multi-core differential transmission cable 221 in the cable width direction are covered with a conductor film 231. As the conductor film 231, a film whose upper and lower surfaces are covered with insulating films 230 and 232 and whose width dimension is slightly larger than the cable height dimension of the multi-core differential transmission cable 221 is used. With the conductor film 231 having such a shape, both ends of the film in the cable height direction are evenly protruded from the ends of the multi-core differential transmission cable 221, and the multi-core differential transmission cable 221 has a cable width direction. Are arranged on both sides 221a.

  Then, as shown in FIG. 18B, the end portions of the conductor film 231 protruding from both ends in the height direction of the multi-core differential transmission cable 221 are joined and electrically connected to each other. The core differential transmission cable 221 is completely covered with the conductor film 231. As a result, the multi-core differential transmission cable 221 is shielded.

  By the way, a transmission cable having a length of 5-10 m or more is required when connecting distant electronic devices with a transmission cable. In such a case, as shown in FIG. It is preferable that the long sheet 220 is preliminarily wound in a roll shape after forming. In this way, when the long sheet 220 is cut, it can be divided by a slicer (not shown) while pulling out the roll-shaped long sheet 220, and a multi-core having a long distance in a limited space. The differential transmission cable 221 can be easily formed.

  Further, instead of separating the roll-shaped long sheet 220 while pulling out, as shown in FIG. 20, the long sheet 220 may be divided in a roll state. In this case, the roll-shaped long sheet 220 can be stored and moved in a divided state, which is convenient for production management.

  Although the laminate sheet A shown in FIG. 16 constitutes only a pair of differential transmission lines, a grounding layer can be added to the construction of the laminate sheet A to add a shielding effect. FIG. 21 shows the configuration of a long sheet on which a laminate sheet with such a grounding layer added is laminated.

  As shown in FIG. 21, in addition to the first conductor sheet 210, the first dielectric sheet 211, and the second conductor sheet 212, the laminate sheet B further includes a third dielectric sheet 214, A third conductor sheet 215 is laminated. The third dielectric sheet 214 and the third conductor sheet 215 are laminated on the surface of the second conductor sheet 212 in this order. The third dielectric sheet 214 and the third conductor sheet 215 may be laminated on the surface of the first conductor sheet 210 in this order. In some cases, the first and second conductor sheets may be stacked. You may laminate | stack on both the conductor sheets 210 and 212. FIG.

  Further, a plurality of laminated sheets B are sequentially laminated with the second dielectric sheet 213 interposed therebetween, thereby forming a long sheet 220 '.

  When the long sheet 220 ′ is cut with a predetermined width, a multi-core differential transmission cable 221 ′ having a pair of differential transmission paths whose upper and lower sides are covered with a third conductor sheet 215 is obtained. That is, by using the third conductor sheet 215 as a ground layer, each differential transmission path of the multi-core differential transmission cable 221 'has a configuration in which at least the top and bottom are shielded.

  The multi-core differential transmission cable 221 has a plurality of differential transmission paths, but the characteristic impedance of each differential transmission path can also be set independently. FIG. 22 shows a configuration of a multi-core differential transmission cable 221 ″ having differential transmission lines having different characteristic impedance values.

  The laminate sheet A1 includes a first conductor sheet 210, a first dielectric sheet 211, and a second conductor sheet 212, and the laminate sheet A2 includes the first conductor sheet 210 ′ and the first conductor sheet 210 ′. 1 dielectric sheet 211 'and 2nd conductor sheet 212'. The characteristic impedance of the differential transmission path is determined by the ratio of h / W2 (h is the distance between the differential transmission paths and W2 is the width of the differential transmission path), but the long sheet 220 ″ is cut at once. Therefore, W2 is constant. Therefore, the characteristic impedance setting can be changed by changing the value of h. h is determined by the thickness of the initial first dielectric sheets 210 and 210 '. Therefore, by individually setting the thickness of the first dielectric sheet 210 of the laminate sheet A1 and the thickness of the first dielectric sheet 210 ′ of the laminate sheet A2, the characteristic impedance of the laminate sheet A1 can be reduced. The value and the value of the characteristic impedance of the laminate sheet A2 can be easily set individually.

  In the multi-core differential transmission cable 221 obtained by dividing the long sheet 220, it is necessary to provide a connector configuration for connecting to an electronic device or another cable at both ends of the cable.

  FIG. 23A, FIG. 23B, FIG. 24A, and FIG. 24B show an example of the configuration of a multi-core differential transmission cable 221 ′ ″ having such a connector configuration and its manufacture. An example of the method is shown.

  FIG. 23A is a top view of the long sheet 220 ″ ″, and FIG. 23B is a cross-sectional view of the long sheet 220 ″ ″ (a laminate sheet is not shown). In these figures, the left-right direction in the figure is the cable longitudinal direction.

  Thick portions 240 are provided at predetermined intervals along the longitudinal direction of the long sheet 220 ″ ″. The thick portion 240 is provided over the entire width of the sheet. The formation interval of the thick portion 240 is set to the desired longitudinal dimension of the multi-core differential transmission cable. In FIGS. 23A and 23B, the longitudinal dimension of the long sheet 220 is set to be a multiple of the longitudinal dimension of the multi-core differential transmission cable, and the thick portion 240 is formed in the cable longitudinal direction interval. A plurality are provided for each. However, when the longitudinal dimension of the long sheet 220 ′ ″ is equal to the longitudinal dimension of the multi-core differential transmission cable, the thick wall portions 240 are provided at both longitudinal ends of the long sheet 220 ′ ″. It is done.

  The thick portion 240 is formed by, for example, selectively increasing the thickness of the second dielectric sheet 213 ′ along the sheet longitudinal direction at the site where the thick portion 240 is formed. In order to selectively increase the thickness of the second dielectric sheet 213 ′ along the longitudinal direction of the sheet, for example, another sheet having the width of the thick part 240 on the formation part of the thick part 240 is provided. A dielectric sheet may be stacked on the second dielectric sheet 213.

  Specifically, as shown in FIG. 23 (A), a width direction dimension W1 equivalent to a dimension obtained by integrating the width dimensions of a plurality of multi-core differential transmission cables and a plurality of multi-core differential transmission cables. A first dielectric sheet 211 having a longitudinal dimension L equivalent to a dimension obtained by integrating longitudinal dimensions is prepared. A first conductor sheet 210 is laminated on one surface of the first dielectric sheet 211, a second conductor sheet 212 is laminated on the other surface, and a second conductor sheet 212 is laminated on the upper surface of the second conductor sheet 212. The dielectric sheet 213 is laminated. As the second dielectric sheet 213, as described above, a sheet having a thick sheet thickness in the longitudinal direction of the sheet is used at the site where the thick portion 240 is formed. After the laminated sheets (first dielectric sheet 211, first conductive sheet 210, second conductive sheet 212, second dielectric sheet 213) thus formed are further laminated in a plurality of stages. Then, the laminate 220 ′ ″ is formed by pressing and integrating the laminate.

  After that, the long sheet 220 ″ ″ is divided for each dimension in the width direction of the multicore differential transmission cable, and further divided for each dimension in the longitudinal direction of the multicore differential transmission cable. At this time, the part of the longitudinal dimension is disposed on the thick part 240. As a result, the plurality of multi-core differential transmission cables 221 ″ ″ are separated from the long sheet 220 ″ ″. Furthermore, the divided thick portion 240 is disposed at the end of the divided multi-core differential transmission cable 221 ″ ″.

  FIG. 24A shows an enlarged cross-sectional view of the vicinity of the end of the multi-core differential transmission cable 221 ″ after the long sheet 220 ″ ″ is divided by the thick portion 240. As shown in FIG. 24A, the second dielectric sheet 213 ′ at the end portion (the thick portion 40 portion) of the multi-core differential transmission cable 221 ′ ″ is the second dielectric sheet of the other portion. Thicker than body sheet 213. Then, as shown in FIG. 24B, only the end portion of the second dielectric sheet 213 ′ is selectively selected at the end portion (the thick portion 240 portion) of the multi-core differential transmission cable 221 ′ ″. By removing the first and second conductor sheets 210 and 212, the first and second conductor sheets 210 and 212 are exposed. As a result, a connector configuration is formed at the end of the multi-core differential transmission cable 221 ″ ″.

  In Embodiment 6 described above, for example, a wholly aromatic aramid film is used as the first dielectric sheet 211 and a polyimide film is used as the second dielectric sheet 213. However, materials such as polyethylene terephthalate, polyphenylene sulfide, and liquid crystal polymer are used. May be used.

(Embodiment 7)
25 (A) to 25 (D) are cross-sectional views in the cable width direction (perpendicular to the length direction) showing the method for manufacturing the flexible differential transmission cable according to the seventh embodiment of the present invention. FIG.

  After forming the first conductive film 311 on the dielectric sheet 310 as shown in FIG. 25A, the dielectric film 312 is formed on the first conductive film 311 as shown in FIG. Form. Further, as shown in FIG. 25C, a second conductive film 313 is formed over the dielectric film 312. Then, as illustrated in FIG. 25D, the second conductive film 313, the dielectric film 312, and the first conductive film 311 are cut to form a strip-shaped groove 314. A plurality of the groove portions 314 are formed in parallel on the dielectric sheet 310 in a state parallel to each other. As a result, a plurality of differential transmission lines 315 made of a laminate of the first conductive film 311, the dielectric film 312 and the second conductive film 313 separated from each other by the groove 314 are formed in parallel with each other. The Here, the signal line formed of the first conductive film 311 and the second conductive film 313 forms a pair of differential signal lines.

  According to the configuration of the seventh embodiment, a plurality of differential transmission lines 315 formed of a laminated body of the first conductive film 311, the dielectric film 312, and the second conductive film 313 separated from each other by the groove 314 are electrically connected. The body sheet 310 and the body sheet 310 can be formed at the same time. For this reason, a flexible differential transmission cable with high productivity can be realized.

  Further, the line width of the pair of signal lines constituting the differential transmission line 315 (the width of the cut first and second conductive films 311 and 313), and the interval between the signal lines (the first and the first signal lines) The distance between the second conductive layers, in other words, the thickness of the dielectric film 312 is formed to be uniform. Therefore, the variation in the characteristic impedance of the differential transmission line can be reduced, and a highly reliable flexible differential transmission cable can be realized.

  Furthermore, if the laminated body which comprises the differential transmission line 315 is formed with the same width and the same space | interval, the multi-core differential transmission cable with the uniform characteristic impedance is realizable. Therefore, a flexible differential transmission cable corresponding to the increase in data capacity can be realized.

  Here, the dielectric sheet 310 and the dielectric film 312 may be any dielectric material that can maintain the flexibility of the differential transmission cable when the differential transmission cable is used. For example, a fully aromatic aramid film in a prepreg state, a polyimide film (thickness is, for example, 30-60 μm), or the like can be used (the same applies hereinafter). The first and second conductive films 311 and 313 can be made of rolled copper foil or the like having the same thickness (for example, 4 to 18 μm).

  Specifically, a polyimide sheet having a thickness of 30 μm is prepared as the dielectric sheet 310, an adhesive is applied on the dielectric sheet 310, and a rolled copper foil of 5 μm is formed thereon as the first conductive film 311. Then, a prepreg of a wholly aromatic aramid film is laminated as a dielectric film 312 thereon, and a 5 μm rolled copper foil is further laminated thereon as a second conductive film 313, which is integrated by heating and pressing. The flexible differential transmission cable 315 can be manufactured by forming the groove 314 with a slicer and making it a desired length.

  Since the characteristic impedance of the differential transmission line 315 is determined by the ratio of (distance between differential transmission lines) / (width of the differential transmission line), the thickness of the dielectric sheet 312 is determined by the differential transmission line. What is necessary is just to set according to the width | variety of 315. FIG.

  The first conductive film 311, the dielectric film 312, and the second conductive film 313 can be cut using a cutter such as a slicer, for example. Note that when cutting with a cutter such as a slicer, a part of the first conductive film 311 is left in order to prevent the first conductive film 311 or the second conductive film 313 from being generated and short-circuiting each other. The cutting is stopped, that is, even if the first conductive film 311 is cut halfway in the thickness direction, a part of the first conductive film 311 is left, and the remaining part of the first conductive film 311 is removed by etching. Good.

  As a cutting adjustment method using a slicer for stopping cutting while leaving a part of the first conductive film 311, for example, as a blade of a slicer, a blade side surface coated with an insulating material or a high resistance material is prepared. One terminal is taken out from the end face of the integrated cable to form the groove 314, and processing is performed while measuring the resistance value with the blade.

  When the tip of the blade cuts the first conductive film 311, the resistance to be measured is low, and when the tip is in the first dielectric film 311, the resistance value is high. Since the thin sheet is cut, the height of the blade to be sliced is adjusted together with the adjustment of the resistance value, so that it can be processed in a desired thickness range. Depending on where the threshold value of the resistance value is set, it is possible to adjust whether the first conductive film 311 is partially left or whether the dielectric sheet 310 is cut deeply.

  Compared to the case where the groove 314 is formed by cutting without leaving the first conductive film 311, a part of the first conductive film 311 remains and the remaining part of the first conductive film 311 is removed by etching. Has the following advantages. That is, if the first conductive film 311 is to be completely cut, the dielectric sheet 310 is partly cut due to processing accuracy. When the dielectric sheet 310 forming the first conductive film 311 is thin, when the flexible differential transmission cable is used, the cut portion of the dielectric sheet 310 is weakened, so that breakage may easily occur. Therefore, it is preferable in terms of strength that the first conductive film 311 is cut while leaving a part, and then the first conductive film 311 is removed by etching. This method is one of the preferable methods when the dielectric sheet 310 is thin.

  In the above method, as an etching solution, a portion to be removed by etching such as a conductive film can be dissolved or decomposed and a dielectric film, a second insulating layer described later, or the like is used (FIG. 28A-FIG. 28 (D)), an etching solution that does not dissolve or decompose these dielectric films or insulating layers may be used. For example, when the above-described dielectric film or conductive film is used, A ferric chloride solution or the like can be used.

  Further, in order to ensure the cutting by the slicer, as shown in FIG. 26, after cutting the first conductive film 311, the dielectric film 312, and the second conductive film 313, the dielectric sheet 310 is further cut. The groove 314 may be formed by cutting a part of the dielectric sheet 310 by biting into a part in the thickness direction. The method described above can be used as a cutting adjustment method using a slicer.

  Even if it does in this way, if the dielectric material sheet 310 is made into sufficient thickness, the integrity of the dielectric material sheet 310 and a some laminated body will not be impaired.

  FIG. 27 shows a flexible differential transmission cable having a more practical structure compared to the flexible differential transmission cable formed by the method shown in FIGS. 25 (A) to 25 (D). It is sectional drawing which shows a structure. FIG. 27 is a cross-sectional view along the cable width direction.

  First, the surface of the flexible differential transmission cable is made flat with no irregularities by embedding the insulator 316 only in the plurality of strip-shaped grooves 314. This state is not shown in FIG. This facilitates handling of the flexible differential transmission cable.

  Further, an insulating layer 317 is formed on the plurality of differential transmission lines 315 and on the plurality of grooves 314 in which the insulator 316 is embedded. Thereby, the entire surface of the plurality of differential transmission lines 315 is protected by the insulator 316 and the insulating layer 317. Note that the insulating layer 317 may be left without being provided with the insulator 316 embedded in the groove 314.

  Here, as the insulator 316 and the insulating layer 317, an insulating material that can maintain flexibility in a state of being a differential transmission cable is used. For example, a fluorine resin such as FEP (tetrafluoroethylene-hexafluoropropylene copolymer resin), an amorphous polyolefin resin, a PEN (polyethylene naphthalate) resin, or the like can be used.

  In addition, after forming the plurality of differential transmission lines 315 having the groove portion 314, by forming the insulating layer 317 on the plurality of differential transmission lines 315 including the groove portion 314, embedding the insulator 316 in the groove portion 314, The insulating layer 317 on the differential transmission line 315 may be formed at the same time.

  Further, as shown in FIG. 27, by forming the ground layer 318 on the insulating layer 317 and by forming the ground layer 319 on the back surface of the dielectric sheet 310, the differential transmission line 315 is connected to the ground layer. A configuration shielded by 318 and 319 can be employed. The material for forming the ground layers 318 and 319 is not particularly limited. For example, a rolled copper foil, an electrolytic copper foil, an aluminum foil, or the like may be laminated, or these metals may be evaporated. May be formed.

  28A to 28D are process cross-sectional views illustrating a method for manufacturing a flexible differential transmission cable according to a modification of the seventh embodiment. These drawings are cross-sectional views along the cable width direction.

  The basic steps of this modification are the same as those shown in FIGS. 25 (A) to 25 (D). However, in the point that a plurality of differential transmission lines 315 shielded by the ground layer can be formed simultaneously with the dielectric sheet 310, the process of the modified example is shown in FIG. This is different from the process shown in FIG.

  First, as shown in FIG. 28A, a first ground layer 320 and a first insulating layer 321 are sequentially formed on the dielectric sheet 310, and then, as shown in FIG. A first conductive film 311, a dielectric film 312, and a second conductive film 313 are sequentially formed over the insulating layer 321. Further, as shown in FIG. 28C, a second insulating layer 322 and a second ground layer 323 are sequentially formed over the second conductive film 313. The material for forming the first ground layer 320 and the second ground layer 323 is not particularly limited, and for example, a rolled copper foil, an electrolytic copper foil, an aluminum foil, or the like may be laminated. Then, these metals may be formed by vapor deposition. Further, the material for forming the first insulating layer 321 and the second insulating layer 322 is not particularly limited, but for example, FEP (tetrafluoroethylene-hexafluoropropylene copolymer resin) or the like Fluorine-based resins, amorphous polyolefin resins, PEN (polyethylene naphthalate) resins, and the like. In order to lower the dielectric constant, it is particularly preferable that the insulating layer has a foamed shape containing a foaming agent.

  Then, as shown in FIG. 28D, the second ground layer 323, the second insulating layer 322, the second conductive film 313, the dielectric film 312 and the first conductive film 311 are cut. A plurality of strip-shaped grooves 314 are formed in parallel on the dielectric sheet 310 in a state parallel to each other. As a result, a plurality of differential transmission lines 315 separated from each other by the groove 314 are formed in parallel. Each differential transmission line 315 includes a stacked body of a first conductive film 311, a dielectric film 312, a second conductive film 313, a second insulating layer 322, and a second ground layer 323.

  According to the method of this modification, a plurality of differential transmission lines 315 separated from each other by the groove 314 are simultaneously formed in a state of being integrated with the dielectric sheet 310. Furthermore, the differential transmission line 315 can be configured to be shielded by the first and second ground layers 320 and 323. Further, similarly to the differential transmission line 315 formed by the method shown in FIGS. 25A to 25D, the line widths of the pair of signal lines constituting the differential transmission line 315 (the cut first And the distance between the signal lines (that is, the distance between the first and second conductive films, in other words, the thickness of the first dielectric film 312). Therefore, the variation in the characteristic impedance of the differential transmission line can be reduced, and a highly reliable flexible differential transmission cable can be realized.

  Note that as described above, a residue (short circuit) of the first conductive film 311, the second conductive film 313, or the second ground layer 323, which may occur when cutting with a cutting tool such as a slicer. In other words, the cutting is stopped while leaving a part of the first conductive film 311, that is, the first conductive film 311 is cut halfway in the thickness direction. The remaining portion of the first conductive film 311 may be removed by etching with the portion remaining.

  Although not shown, the second ground layer 323, the second insulating layer 322, the second conductive film 313, and the dielectric are used in order to ensure the cutting by the slicer, as described with reference to FIG. After the film 312 and the first conductive film 311 are cut, a part of the first insulating layer 321 may be cut into the thickness direction and cut to form the groove portion 314.

  FIG. 29 shows that a flexible differential transmission cable formed by the method shown in FIGS. 28 (A) to 28 (D) is embedded in at least a groove portion 314 to embed an insulator 316, thereby allowing flexible differential transmission. It is sectional drawing of the cable width direction (direction perpendicular | vertical to a length direction) which shows the structure which made the surface of the cable the flat surface without an unevenness | corrugation.

  In order to protect the second ground layer 323, an insulating layer 317 is further provided on the plurality of differential transmission lines 315 and the plurality of grooves 314 in which the insulator 316 is embedded, as clearly shown in FIG. It may be formed.

(Embodiment 8)
In a high density circuit board, a connection structure corresponding to an input / output terminal which increases with high density is required. In such a demand, how to connect an input / output terminal formed on the high density circuit board? An important issue is whether to connect to other circuit boards with high reliability.

For example, in a signal transmission cable used for signal propagation in a notebook computer or a mobile phone that includes two components and is configured to be foldable,
-The input / output terminals formed with a fine wiring pitch can be electrically connected to each other with high connection reliability on the circuit boards of the two components that make up a notebook computer, mobile phone, etc.
-With materials and structures that can withstand bending;
There is a request.

  Conventionally, there is a signal transmission cable disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-134845 as a signal transmission cable that meets the above demand. In this signal transmission cable, a plurality of wirings are patterned on one or both sides of a flexible substrate formed of a polyimide film, and connection terminals are formed on both ends thereof.

  FIG. 30 shows a configuration of the flexible signal transmission cable 700 described in the above-mentioned patent document. The flexible signal transmission cable 700 connects, for example, two circuit boards provided in two components of a foldable mobile phone. The flexible signal transmission cable 700 is provided with an insulating substrate 701. The insulating substrate 701 has a shape for avoiding bending stress concentration during the folding operation of the mobile phone. A plurality of wirings 702 are formed on the insulating substrate 701 in parallel with each other with a predetermined pitch. Terminals 703 are provided at both ends of each wiring 702.

  In order to increase the number of wirings 702 in accordance with the increase in the number of input / output terminals of the circuit board, it is necessary to form the wirings 702 on both surfaces of the insulating substrate 701 or to reduce the pitch of the wirings 702.

However, when the number of wirings 702 is increased, the number of terminals 703 formed at both ends of the wiring 702 increases, so that the area of the signal transmission cable 700 increases. For this reason, it becomes impossible to connect with a plurality of circuit boards at a high density with a limited area.
Further, even if the pitch of the wiring 702 is made fine, if a large land is not provided in the terminal portion of the wiring, it is difficult to align and connect with other circuit boards to be connected. It becomes a factor that inhibits high density.

  On the other hand, when transmitting a high-frequency signal, due to the skin effect of the conductor constituting the wiring 702, for example, the depth of the skin of the conductor necessary for transmitting a signal of 500 MHz is 3 μm. The depth is 2 μm. Since the conductor thickness of the wiring 702 is about 40 μm, only 2-3 μm of about 40 μm is used for transmitting a high-frequency signal. Accordingly, the transmission utilization efficiency per cross-sectional area of the conductor that transmits the high-frequency signal is extremely poor.

  FIGS. 31A and 31B are a perspective view and a cross-sectional view showing the signal transmission cable 600 of the present invention described in the first embodiment and the like described above. As shown in FIG. 31A, the signal transmission cable 600 is composed of a laminate sheet in which a plurality of conductor sheets 501 and insulator sheets 502 are alternately laminated. As shown in FIG. 31 (B), the end portions 501a to 501g of the respective conductor sheets 501 are formed in a stepped shape via the insulating sheet 502, and the end portions 501a to 501g are formed on the respective conductor sheets. It becomes an electrode terminal for taking out the signal line 501.

The conductor sheet 501 and the insulator sheet 502 are formed on the surface of the support substrate by a method such as vacuum deposition, sputtering, or CVD, for example. The electrode terminals 501a to 501g formed in a step shape are formed in a process in which the conductor sheet 501 and the insulator sheet 502 are multilayered by repeated vapor deposition or the like.
A step of depositing the conductor sheet 501 by covering the end of the insulator sheet 502 that does not require the conductor sheet 501 with a resist;
A step of depositing the insulator sheet 502 by covering the end of the conductor sheet that does not require the insulator sheet 502 with a resist;
It can be formed by removing the resist after repeating the above two steps.

  Since the conductor sheet 501 and the insulator sheet 502 formed by this method can be as thin as about 0.5-2 μm, for example, even if 50 layers of the conductor sheets 501 are stacked, the thickness is 200 μm or less. Become. Therefore, the signal transmission cable can sufficiently exhibit flexibility.

  Alternatively, a rolled copper foil (for example, 5 μm) is used as the conductor sheet 501, and a prepreg wholly aromatic aramid film having a predetermined thickness (for example, 30 μm) is used as the insulating sheet 502, by heating and pressurizing or the like. It can also be formed by bonding. This method has an advantage that it can be manufactured at a low cost although the thickness is increased as compared with a method by vapor deposition or the like. Further, since the conductor sheet 501 and the insulator sheet 502 can be formed thick, it is easy to obtain a desired circuit constant.

  Thus, the signal transmission cable 600 can provide a signal transmission cable with high wiring density and excellent flexibility. However, since the electrode terminals 501a to 501g for taking out the signal lines are formed in a stepped shape, it is necessary to prepare a special connector suitable for the stepped shape in terminal connection with other circuit boards and the like. This is a problem in putting the signal transmission cable 600 into practical use.

  Such a problem of the signal transmission cable 600 can be solved by taking the configuration of the electrode terminals shown in FIGS. 32 (A) and 32 (B). In FIG. 32A, a protective layer 503 that covers the stepped electrode terminals 501a to 501g at the end of the signal transmission cable 600 is formed, and via hole conductors 504a connected to the electrode terminals 501a to 501g are formed on the protective layer 503. After forming -504g, a plurality of lands 505 are formed on each via-hole conductor 504a-504g. Accordingly, the electrode terminals 501a to 501g can be extended to the same plane as the surface of the signal transmission cable 600.

  In FIG. 32B, bumps 506a-506g are formed on the stepped electrode terminals 501a-500g. The heights of the bumps 506a to 506g are aligned so as to be in the same plane as the surface of the signal transmission cable 600. Accordingly, the electrode terminals 501a to 501g can be extended to the same surface as the surface of the signal transmission cable 600.

  32A and 32B, via-hole conductors 504a- that extend from the electrode terminals 501a-501g of the conductor sheet 501 formed in a staircase shape to the same plane as the surface of the signal transmission cable. By connecting to 504g and bumps 506a to 506g, connection with other circuit boards can be facilitated.

  However, such a structure requires an extra process for forming the via-hole conductors 504a-504g and the bumps 506a-506g, leading to an increase in the cost of the signal transmission cable. Further, the connection between the stepped electrode terminals 501a to 501g and the via hole conductors 504a to 504g and the bumps 506a to 506g may reduce reliability.

  In view of such a problem, the eighth embodiment proposes electrode terminals arranged in the same plane as the surface of the signal transmission cable by a simple method.

  Embodiment 8 will be described below with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of simplicity. In addition, this invention is not limited to the following embodiment.

  33 (A) to 33 (C) are process cross-sectional views illustrating the method for manufacturing the signal transmission cable 610 according to the eighth embodiment of the present invention.

  First, as illustrated in FIG. 33A, the conductor sheets 510 and the insulator sheets 520 are alternately stacked so that the end portions of the conductor sheets 510 and the insulator sheets 520 are stepped surfaces. A body sheet 610 is created.

  The floor section is formed as follows. That is, the sheet end portion of the sheet sheet 610b of the laminate sheet 610 is located closer to the end of the conductor sheet 510 and the end of the insulator sheet 520 on the other sheet surface 610c side. A staircase surface is formed on one sheet surface 610b of the sheet end portion 610a by arranging in a staircase shape so as to be on the 610a side.

  Here, the end portions 510 a to 510 d of the respective conductor sheets that are sequentially exposed on the staircase surface of the laminate sheet 6110 constitute electrode terminals of the signal transmission cable 620.

  Next, as shown in FIG. 33B, the resin member 530 is brought into contact with the other sheet surface 610c (the sheet surface on the lowermost layer sheet 520a side in the drawing) at the end 610a of the laminate sheet 610. The shape of the resin member 530 is not particularly limited, but the resin member 530 has a shape corresponding to the shape of the end portion of the stacked body 610 that disappears due to the formation of the staircase (a triangular shape in cross section in FIG. 33A). Is preferred.

  With the resin member 530 in contact with the laminate sheet 610, the resin member 530 and the laminate sheet 610 are pressed along the direction of the arrow (sheet thickness direction) in FIG. Then, as shown in FIG. 33C, the laminate sheet 610 and the resin member 530 are in pressure contact so that the stepped surface of the laminate sheet 610 is flush with the surface of the uppermost layer sheet 520e of the laminate sheet. Further, the end 610a of the laminate sheet 610 is deformed. Thereby, the electrode terminals 510a to 510d formed in a step shape are arranged along the surface of the uppermost layer sheet 520e, that is, the surface of the signal transmission cable 620 in the drawing of the laminate sheet 610.

  Here, the shape of the resin member 530 is set to a shape corresponding to the shape of the end portion of the laminate 610 that disappears due to the formation of the staircase, in other words, the one surface 530a of the resin member 530 that contacts the laminate sheet 610. If the shape of the resin member 530 is set so that the other surface 530b located on the opposite side of the other side 530b is substantially parallel to the stepped surface of the laminate sheet 610, when the end portion of the laminate sheet 610 is deformed, As shown in FIG. 33C, the other surface 530b of the resin member 530 is substantially flush with the other sheet surface 610c of the laminate sheet 610, and the back surface of the signal transmission cable 620 is flattened.

  If the resin member 530 is made of a semi-cured B-stage resin made of a thermosetting epoxy resin or polyolefin resin, the resin member 530 is cured after the resin member 530 is mounted on the laminate sheet 610. By doing so, the resin member 530 and the laminate sheet 610 can be easily integrated.

  Furthermore, when the end portion of the laminate sheet 610 is deformed, it is preferable to arrange a flat plate 640 on one sheet surface 610b of the laminate sheet 610, as shown in FIG. Then, when pressing the resin member 530, the one sheet surface 610b (step surface) of the laminate sheet 610 is brought into contact with the flat plate 540, whereby the step surface of the laminate sheet 610 and the one sheet surface 610b Can be easily performed on the same plane.

  In the signal transmission cable 620 formed by the manufacturing method described above, the electrode terminals 510a to 510d are provided on the same surface as the end portion of the one surface 610b of the cable. Therefore, the terminal connection with other circuit boards and the like can be facilitated, and the conventional connector can be used as it is for the connection with other electrical structures such as the circuit boards, and the manufacturing of the connection structure accordingly. Cost can be reduced.

  Further, the flatness of the electrode terminals 510a-510d can be achieved by simply pressing the resin member 530 without providing the via-hole conductors 504a-504g and the bumps 506a-506g shown in FIGS. 32 (A) and 32 (B). In addition, since no extra connection points are generated, a high-quality signal transmission cable with high productivity can be obtained.

  Here, the conductor sheet 510 and the insulator sheet 520 are formed on the surface of the support substrate by a method such as vacuum deposition, sputtering, or CVD, for example. The stepped electrode terminals 510a to 510d are formed by the same method as described above with reference to FIGS. 31 (A) and 31 (B).

  Since the conductor sheet 510 and the insulator sheet 520 formed by vapor deposition can be as thin as about 0.5-2 μm, for example, even when 50 conductor sheets 510 are stacked, the thickness is 200 μm or less. . Therefore, the signal transmission cable 620 can exhibit sufficient flexibility.

  When a signal transmission cable is formed by combining a conductor sheet 510 made of rolled copper foil and an insulator sheet 520 made of a fully aromatic aramid film in a prepreg state, the thickness is increased as compared with a method using vapor deposition or the like. However, there is a merit that it can be manufactured at low cost. Further, since the conductor sheet 510 and the insulator sheet 520 can be formed thick, it is easy to obtain a desired circuit constant.

  FIG. 34 shows a top view of the signal transmission cable 620 having the cross-sectional structure shown in FIG. At the end of the laminate sheet 620, the electrode terminals 510a to 510d are exposed in a band shape in the width direction of the signal transmission cable 620. Between each electrode terminal 510a-510d, the insulator sheet | seats 520a-520d which are similarly strip-shaped and exposed are provided. Therefore, the electrode terminals 510a-510d are electrically separated by the insulator sheets 520a-520d. Note that the conductor sheet 510 can have a sufficiently large width, so that the resistance of the signal line is not increased by making the conductor sheet 510 thinner.

FIG. 35 shows a top view of a signal transmission cable 620 in which two signal lines are formed on each conductor sheet 510. As shown in FIG. 35, the signal lines having the width W are formed in parallel, and the electrode terminals 510a _{1 to} 510d ₁ and the electrode terminals 510a _{2 to} 510d ₂ of the signal lines are provided at the end of the laminate sheet. , Each is exposed independently. In this way, by forming a plurality of signal lines on each conductor sheet 510, a high-density signal transmission cable 620 can be obtained.

  36 (A) and 36 (B) show a method of manufacturing a signal transmission cable 630 in which the resin member 530 shown in FIGS. 33 (B) and 33 (C) is also used as a reinforcing material for the laminate sheet 610. It is process sectional drawing which shows these.

  First, as shown in FIG. 36A, in a state where the resin member 531 is in contact with the other sheet surface 610c of the laminate sheet 610, the resin member 531 and the laminate sheet 610 are joined together as shown in FIG. Is pressed along the direction of the arrow (sheet thickness direction). The resin member 531 includes a flat plate-like main body 531a that receives the laminate sheet 610, and an inclined portion 531b that is provided at the end of the main body 531a and receives the end of the laminate sheet 610. The inclined portion 531b has a shape corresponding to the shape of the end portion of the stacked body 630 that disappears due to the formation of the staircase surface.

  When the resin member 531 is pressed against the laminate sheet 610, as shown in FIG. 36B, the laminate sheet 610 and the resin member 531 are in pressure contact, and the stepped surface of the laminate sheet 610 is one sheet of the laminate sheet 610. The edge part of the laminated body sheet | seat 610 deform | transforms so that it may become the same surface as a surface. Thereby, the electrode terminals 510a to 510d formed in a step shape are arranged along the surface of the uppermost layer sheet 520e, that is, the surface of the signal transmission cable in the drawing of the laminate sheet 630.

  Moreover, the resin member 531 can be used as a reinforcing material for the laminate sheet 610 by attaching the resin member 531 to the entire laminate sheet 610.

  FIG. 37A and FIG. 37B are cross-sectional views showing the arrangement of electrode terminals when the electrode terminals of the conductor sheet 610 are provided at both ends of the laminate sheet 610. 37A and 37B are cross-sectional views along the longitudinal direction of the conductor sheet. 37A and 37B, reference numerals 550a and 550b denote regions of the laminate sheet 610 in which the electrode terminals are exposed. Regions 550a and 550b are provided at both ends of the sheet.

  In the configuration of FIG. 37A, the regions 550a and 550b are arranged on the same sheet surface (one sheet surface 610b) of the laminate sheet 610. The resin member 530 is formed on the sheet surface (the other sheet surface 610c) located on the opposite side of the regions 550a and 550b.

  In the configuration of FIG. 37B, the regions 550a and 550b are disposed on the different sheet surfaces 610b and 610c of the laminate sheet 610, respectively. The resin members 530 and 530 are disposed on the sheet surfaces 610c and 610b located on the opposite sides of the regions 550a and 550b.

  By appropriately arranging the regions 550a and 550b for exposing the electrode terminals in this manner, connection to other circuit boards and the like can be facilitated.

  FIG. 38 shows a configuration when the signal transmission cable 620 formed according to the eighth embodiment is used for connection between the circuit boards 560a and 560b. Since the signal transmission cable 620 is highly flexible, for example, even when used in an electronic device such as a notebook computer or a mobile phone that can be folded, a highly reliable electrical connection can be realized.

  FIG. 39 shows a top view of the signal transmission cable 650 formed as described above. Signal line electrode terminals 550a and 550b are exposed in regions 550a and 550b at both ends of the cable. As shown in FIG. 39, a plurality of signal transmission cables can be formed at the same time by cutting with a certain width along the longitudinal direction (direction of dotted line PQ) of the laminate sheet. Thereby, an inexpensive signal transmission cable can be obtained easily.

  Although the eighth embodiment has been described above, this description is not a limitation and, of course, various modifications can be made. For example, although the example in which the conductor sheet 510 is formed as a signal line has been described, a part of the conductor sheet 510 can also be used as a shield layer in order to reduce noise generation.

  The eighth embodiment is a technique suitable for a signal transmission cable that enables a plurality of circuit boards and the like to be connected with high density, but the technique can also be applied to a wiring board. That is, the resin member is brought into contact with the sheet end located on the side that is not the staircase surface of the laminate sheet, the resin member is pressed, and the staircase surface of the laminate sheet becomes the uppermost layer of the laminate sheet. A wiring board can be manufactured by deforming the end of the laminate sheet so as to be in the same plane.

  Here, the end portion of the conductor sheet exposed on the staircase surface of the laminate sheet constitutes the electrode terminal of the wiring board, and the electrode terminal is connected to the surface of the laminate sheet by deforming the end portion of the laminate sheet. Arranging on the same plane is exactly the same as the signal transmission cable.

  According to the present invention, it is possible to provide a signal transmission cable that can connect a plurality of circuit boards and the like with high density.

The figure which shows the structure of the signal transmission cable of Embodiment 1 of this invention. The figure which shows the manufacturing method of the signal transmission cable of Embodiment 1, respectively. FIG. 3 is a diagram illustrating a configuration of another signal transmission cable according to the first embodiment. FIG. 6 is a diagram illustrating a configuration of still another signal transmission cable according to the first embodiment. The figure which shows the structure of the signal transmission cable of Embodiment 2 of this invention. FIG. 6 is a diagram illustrating a method for manufacturing the signal transmission cable according to the second embodiment. The figure which shows the structure of the signal transmission cable of Embodiment 3 of this invention. The figure which shows the structure of the other signal transmission cable of Embodiment 3. FIG. The figure which each shows the manufacturing method of the signal transmission cable of Embodiment 4 of this invention. The figure which shows the manufacturing method of the other signal transmission cable of Embodiment 4. FIG. The figure which shows the structure of the transmission core cable of Embodiment 5 of this invention. FIG. 10 is a diagram illustrating a configuration of a connector of a signal transmission cable according to a fifth embodiment. A first example of the shape of the first and second conductive layers. A second example of the shape of the first and second conductive layers. The figure which each shows the manufacturing method of the multi-core differential transmission cable of Embodiment 6 of this invention. FIG. 10 is a diagram illustrating a method for cutting a long sheet according to a sixth embodiment. Sectional drawing and the one part enlarged view of the multi-core differential transmission cable of Embodiment 6. FIG. The figure which shows the shield structure of the multi-core differential transmission cable of Embodiment 6. FIG. FIG. 9 is a diagram illustrating a method for cutting a roll-shaped long sheet according to a sixth embodiment. FIG. 10 shows another cutting method for a roll-like long sheet according to the sixth embodiment. Sectional drawing which shows the structure of the other long sheet | seat of Embodiment 6. FIG. Sectional drawing which shows the structure of the other elongate sheet | seat of Embodiment 6. FIG. The figure which shows the connector formation method of the multi-core differential transmission cable of Embodiment 6; The enlarged view which shows the connector structure of the multi-core differential transmission cable of Embodiment 6, respectively. Sectional drawing of process of the orthogonal | vertical direction with respect to the cable length direction which each shows the manufacturing method of the flexible differential transmission cable of Embodiment 7 of this invention. Sectional drawing which shows an example of the cutting method of the groove part of Embodiment 7. FIG. FIG. 9 is a cross-sectional view illustrating a configuration of a shielded flexible differential transmission cable according to a seventh embodiment. Process sectional drawing which each shows the manufacturing method of the other flexible differential transmission cable of Embodiment 7. FIG. FIG. 29 is a cross-sectional view showing a configuration of a flexible differential transmission cable formed by the manufacturing method of FIG. 28 and further flattened. The top view which shows the structure of the reference example of a flexible signal transmission cable. The perspective view and sectional drawing which show the structure of the signal transmission cable which is Embodiment 8 of this invention in which the electrode terminal was formed in step shape. Sectional drawing which each shows the method of planarizing a step-like electrode terminal. Process sectional drawing which shows the manufacturing method of the signal transmission cable of Embodiment 8. FIG. FIG. 10 is a top view of a signal transmission cable according to an eighth embodiment. FIG. 20 is a top view of another signal transmission cable according to the eighth embodiment. Process sectional drawing which shows the manufacturing method of the other signal transmission cable of Embodiment 8, respectively. Sectional drawing which shows arrangement | positioning of the electrode terminal of the signal transmission cable of Embodiment 8, respectively. The figure which shows the structure which used the signal transmission cable of Embodiment 8 for the connection between circuit boards. FIG. 10 is a diagram illustrating a method for manufacturing a signal transmission cable according to an eighth embodiment. The figure which shows the structural example of the conventional flexible multicore cable. The figure which shows the structural example of the conventional multi-core coaxial cable, respectively. The figure which shows the manufacturing method of the conventional multi-core coaxial cable, respectively. The figure which shows the structure of the conventional signal transmission cable. The figure which shows the structure of the conventional multi-core signal transmission cable. The figure which shows the manufacturing method of the conventional multi-core signal transmission cable.

Explanation of symbols

100 Signal Transmission Cable 10 Dielectric Core Layer 10 ′ Dielectric Core Sheet 10a Dielectric Core Layer 10b Dielectric Core Layer 11 First Conductive Layer 11 ′ First Conductive Sheet 12 Second Conductive Layer 12 ′ Second Conductor sheet 13 Insulator 14 Shield layer 15 Sheath 16 First dielectric layer 16 ′ First dielectric sheet 17 Second dielectric layer 17 ′ Second dielectric sheet 18 First grounding conductive layer 18 'First ground sheet 19 Second conductive layer 19' Second ground sheet 20 Transmission core cable 21 Transmission core cable 30 Insulation layer 31 Drain wire 40 Dielectric sheet 41 Insulation sheet 42 Grounding conductive film 43 For grounding Conductive film 44 Sheath 45 Sheath 50 First dielectric sheet 51 Second dielectric sheet 60 Connector 61 Conductive clip 130 Signal transmission cable 140 Signal transmission cable 15 Signal transmission cable 160 Signal transmission cable 170 Signal transmission cable 210 First conductor sheet 211 First dielectric sheet 212 Second conductor sheet 213 Second dielectric sheet 213 ′ Second dielectric sheet 214 Third Dielectric sheet 215 Third conductor sheet 220 Long sheet 220 ′ Long sheet 220 ″ Long sheet 220 ′ ″ Long sheet 221 Multi-core differential transmission cable 221 ′ Multi-core differential transmission cable 221 ′ 'Multi-core differential transmission cable 221''' Multi-core differential transmission cable 231 Conductor film 230 Insulating film 232 Insulating film 240 Thick part 310 Dielectric sheet 311 First conductive film 312 Dielectric film 313 Second conductive film 313
314 Groove 315 Differential transmission line 316 Insulator 317 Insulation layer 318 Ground layer 319 Ground layer 320 First ground layer 321 First insulation layer 322 Second insulation layer 323 Second ground layer 501 Conductive sheets 501a-501g Electrode terminal (end of conductor sheet 501)
502 Insulator sheet 503 Protective layer 504a-504g Via-hole conductor 505 Land 506a-506g Bump 510 Conductor sheet 510a-510d Electrode terminal (sheet end)
520 Insulator sheet 530 Resin member 531 Resin member 531a Main body 531b Inclined portion 550a Laminate sheet 610 region 550b Laminate sheet 610 region 600 Signal transmission cable 610 Laminate sheet 610a Sheet end portion 610b One sheet surface 610c The other sheet Surface 620 Signal transmission cable 630 Laminate body 640 Flat plate 650 Signal transmission cable A Laminate sheet A1 Laminate sheet A2 Laminate sheet B Laminate sheet

Claims (25)

A dielectric core layer extending along the longitudinal direction of the cable;
A first conductive layer laminated on one surface of the dielectric core layer;
A second conductive layer laminated on the other surface of the dielectric core layer;
An insulator covering the dielectric core layer and the first and second conductive layers;
A conductive shield layer covering the insulator;
An insulating sheath further covering the conductive shield layer;
Have
The dielectric core layer and the first and second conductive layers have the same width.
The first and second conductive layers have the same thickness;
Signal transmission cable. The first and second conductive layers constitute a pair of differential signal lines.
The signal transmission cable according to claim 1. A first dielectric layer is laminated on the first conductive layer, and a first grounding conductive layer is laminated on the first dielectric layer,
A second dielectric layer is laminated on the second conductive layer, and a second grounding conductive layer is laminated on the second dielectric layer,
The first dielectric layer, the first grounding conductive layer, the second dielectric layer, and the second grounding conductive layer include the dielectric core layer, the first conductive layer, and Having the same width as the second conductive layer;
The first dielectric layer and the second dielectric layer have the same thickness.
The signal transmission cable according to claim 1. The thickness of the dielectric core layer is thinner than the thickness of the first and second dielectric layers,
The signal transmission cable according to claim 3. A plurality of the transmission core cables, and the plurality of transmission core cables are enclosed in the insulator;
The signal transmission cable according to claim 1. The dielectric core layer is made of any one of polyimide, wholly aromatic polyamide, polyethylene terephthalate, polyphenylene sulfide, and liquid crystal polymer.
The signal transmission cable according to claim 1. The first conductive layer and the second conductive layer have different surface colors or shapes,
The signal transmission cable according to claim 3. Providing a dielectric core sheet having a sheet length equal to or longer than the cable length and a sheet width equal to or wider than multiple times of the cable width;
A step of laminating a conductor sheet on each of both surfaces of the dielectric core sheet to cover the both surfaces;
Dividing the dielectric core sheet by a cable width and simultaneously forming a plurality of transmission core cables;
Encapsulating each of the plurality of transmission core cables with an insulator;
including,
A method for manufacturing a signal transmission cable. After dividing the dielectric core sheet to form a plurality of transmission core cables, the step of removing the residue of the conductor sheet remaining in the split section of the transmission core cable,
In addition,
The method for manufacturing a signal transmission cable according to claim 8. Providing a dielectric core sheet having a sheet length equal to or longer than the cable length and a sheet width equal to or wider than multiple times of the cable width;
A step of laminating a conductor sheet on each of both surfaces of the dielectric core sheet to cover the both surfaces;
Laminating a dielectric sheet on each of the conductor sheets and covering the conductor sheet;
A step of laminating a grounding conductor sheet on each of the dielectric sheets to cover the dielectric sheet;
Dividing the dielectric core sheet by a cable width and simultaneously forming a plurality of transmission core cables;
Encapsulating each of the plurality of transmission core cables with an insulator;
A method of manufacturing a signal transmission cable including: A first conductor sheet, a first dielectric sheet, and a second conductor sheet each having a longitudinal dimension equal to or longer than the cable longitudinal dimension and a width dimension equal to or wider than a plurality of times of the cable width dimension; The step of forming a laminate sheet by laminating the conductor sheets in this order,
Forming a long sheet by sequentially laminating a plurality of the laminate sheets with a second dielectric sheet interposed therebetween;
A step of winding the long sheet into a roll,
A step of separating while pulling out a sheet end from the long sheet wound in a roll,
Of manufacturing a multi-core differential transmission cable including: As a pre-process for dividing the long sheet, including a step of winding the long sheet into a roll,
The step of dividing the long sheet is divided while pulling out the sheet end from the long sheet wound in a roll shape,
The manufacturing method of the multi-core differential transmission cable of Claim 11. A first conductor sheet, a first dielectric sheet, and a second conductor sheet each having a longitudinal dimension equivalent to the cable longitudinal dimension and a width dimension equivalent to the cable width dimension are laminated in this order. A laminate sheet comprising:
The first conductor sheet and the second conductor sheet have the same thickness,
The laminate sheet is obtained by laminating a third dielectric sheet and a third conductor sheet in this order on at least one surface of the first and second conductor sheets.
A plurality of the laminate sheets are sequentially laminated with a second dielectric sheet interposed therebetween,
The first conductor sheet and the second conductor sheet constitute a pair of differential transmission lines arranged with the first dielectric sheet interposed therebetween,
The third conductor sheet constitutes a ground wire;
Multi-core differential transmission cable. A connector at the end of the cable
The connector has a thick portion where the thickness of the second dielectric sheet is thicker than other sheet portions.
The multi-core differential transmission cable according to claim 13. A part of the second dielectric sheet in the thick part is deleted, and the first and second conductor sheets are exposed;
The multi-core differential transmission cable according to claim 14. Forming a first conductive film on a flexible dielectric sheet;
Forming a dielectric film on the first conductive film;
Forming a second conductive film on the dielectric film;
By cutting the second conductive film, the dielectric film, and the first conductive film, a plurality of strip-shaped grooves are formed in parallel on the dielectric sheet, and between the adjacent grooves, Forming a differential transmission line comprising a laminate of the first conductive film, the dielectric film, and the second conductive film separated by a groove;
After forming the differential transmission line, embedding an insulator in the groove,
Including
The groove portions are formed to have the same width, and the differential transmission line is configured by the stacked body having the same width.
Manufacturing method of flexible differential transmission cable. A step of covering the groove embedded with the insulator and the differential transmission line with an insulating layer;
The method of manufacturing a flexible differential transmission cable according to claim 16. Forming a ground layer on the insulating layer;
The method of manufacturing a flexible differential transmission cable according to claim 17. Forming a ground layer on the back surface of the dielectric sheet;
The method of manufacturing a flexible differential transmission cable according to claim 16. The step of forming the groove portion is performed by cutting the second conductive film, the dielectric film, and the first conductive film halfway in the thickness direction so that a part of the first conductive film remains. After forming the strip-shaped groove, the remaining portion of the first conductive film is removed by etching,
The method of manufacturing a flexible differential transmission cable according to claim 16. A conductor sheet and an insulator sheet are alternately stacked to form a laminate sheet, and at one sheet surface of the sheet end of the laminate sheet, the end of the conductor sheet and the insulator sheet A first step of forming a stepped surface on the one sheet surface of the sheet end portion by arranging the end portion in a stepped manner so that the sheet located on the other sheet surface side is closer to the sheet end portion side. Process,
A second step of bringing a resin member into contact with the other sheet surface of the sheet end of the laminate sheet;
By pressing the resin member along the sheet thickness direction, the stepped surface is deformed so that the staircase surface is flush with the one sheet surface, so that it is flush with the one sheet surface. A third step of configuring an electrode terminal from each of the conductor sheets exposed to the stepped surface,
A method of manufacturing a signal transmission cable including: As the resin member, when the resin member is brought into contact with the other sheet surface, the other surface of the resin member located on the opposite side of the one surface of the resin member in contact with the other sheet surface, Using a shape that is substantially parallel to the step surface,
In the third step, the sheet end is deformed so that the other surface of the resin member is flush with the other sheet surface of the laminate sheet.
The method for manufacturing a signal transmission cable according to claim 21. The resin member is composed of a semi-cured resin, and further includes a step of curing the resin member and integrating the resin member and the laminate sheet after the third step.
The method for manufacturing a signal transmission cable according to claim 21. As the resin member, one having a size that contacts the entire surface of the laminate sheet is used.
The method for manufacturing a signal transmission cable according to claim 21. In the third step, in a state where a flat plate is brought into contact with the one sheet surface of the sheet end of the laminate sheet, the resin member is pressed along the sheet thickness direction.
The method for manufacturing a signal transmission cable according to claim 21.

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